diff --git a/backend/prisma/migrations/20260514_add_mail_blocked_trigger_source/migration.sql b/backend/prisma/migrations/20260514_add_mail_blocked_trigger_source/migration.sql
new file mode 100644
index 0000000..c6c728d
--- /dev/null
+++ b/backend/prisma/migrations/20260514_add_mail_blocked_trigger_source/migration.sql
@@ -0,0 +1,18 @@
+-- Migration: add_mail_blocked_trigger_source
+-- Fügt trigger_source zu mail_blocked hinzu — trackt welcher Klassifikations-Layer
+-- die Blockierung ausgelöst hat (Layer 2 "domain", Layer 2.5 "brand+random",
+-- Layer 3 "score:NN", Layer 4 "llm:0.XX").
+--
+-- Breaking-change status: NONE.
+-- Spalte ist nullable — alle bestehenden Rows erhalten NULL (= "unbekannt", vor Migration).
+-- Kein Backfill notwendig: historische Daten ohne trigger_source bleiben NULL.
+--
+-- Deploy: automatisch via GitHub Actions (pnpm prisma migrate deploy)
+
+ALTER TABLE "rebreak"."mail_blocked"
+  ADD COLUMN "trigger_source" VARCHAR(64);
+
+-- Index für spätere Auswertungen (z.B. "wie viele LLM-Blocks vs. Domain-Blocks pro User?")
+CREATE INDEX "mail_blocked_trigger_source_idx"
+  ON "rebreak"."mail_blocked" ("trigger_source")
+  WHERE "trigger_source" IS NOT NULL;
diff --git a/backend/prisma/migrations/20260514_add_mail_classification_sample/migration.sql b/backend/prisma/migrations/20260514_add_mail_classification_sample/migration.sql
new file mode 100644
index 0000000..28800cc
--- /dev/null
+++ b/backend/prisma/migrations/20260514_add_mail_classification_sample/migration.sql
@@ -0,0 +1,72 @@
+-- Migration: add_mail_classification_sample
+-- Neue Tabelle für ML-Phase 3: Klassifikations-Samples pro Mail-Analyse.
+-- Speichert Features + Outcomes für zukünftiges Fine-Tuning und Modell-Evaluation.
+--
+-- DSGVO-Compliance:
+--   - KEIN Mail-Body (Art. 9 Datenminimierung).
+--   - subject + sender_name: kurzlebige Detection-Signale, kein narrativer Inhalt.
+--     Werden mit Mail-Flush nach 24h in mail_blocked bereinigt — Samples bleiben
+--     länger erhalten (Forschungszweck), sind aber auf Domain/Score-Features reduziert.
+--   - Cascade-Delete bei User-Löschung: user_id referenziert profiles.id (Art. 17).
+--     Da profiles kein FOREIGN KEY auf mail_classification_samples hat (userId als
+--     losgelöste UUID), wird Cascade via RLS-Trigger oder bei Account-Lösch-Routine
+--     sichergestellt (deleteAllMailConnections-Äquivalent für Samples).
+--     Alternativ: manuelle DELETE in Account-Lösch-Endpoint (backend/server/api/...).
+--     TODO: Account-Lösch-Flow prüfen ob Samples mitgelöscht werden.
+--
+-- Breaking-change status: NONE.
+-- Neue Tabelle, kein Impact auf bestehende Queries.
+--
+-- Deploy: automatisch via GitHub Actions (pnpm prisma migrate deploy)
+
+CREATE TABLE "rebreak"."mail_classification_samples" (
+  "id"                   TEXT         NOT NULL,
+  "user_id"              UUID         NOT NULL,
+  "connection_id"        UUID,
+
+  -- Raw features (Detection-Signale, keine PII über Inhalt)
+  "sender_name"          VARCHAR(255),
+  "sender_domain"        VARCHAR(255),
+  "relay_decoded_domain" VARCHAR(255),
+  "subject"              VARCHAR(998),  -- RFC 5322 max subject length
+
+  -- Computed features (Score-Komponenten als JSON)
+  "features"             JSONB        NOT NULL DEFAULT '{}',
+
+  -- Outcome
+  "final_action"         TEXT         NOT NULL,  -- "blocked" | "passed"
+  "trigger_source"       TEXT         NOT NULL,  -- "domain" | "brand+random" | "score:NN" | "llm:0.XX" | "whitelist" | "no-signal"
+
+  -- Groq verdict (NULL wenn Layer 4 nicht lief)
+  "groq_is_gambling"     BOOLEAN,
+  "groq_confidence"      DOUBLE PRECISION,
+  "groq_reason"          TEXT,
+
+  -- User-Feedback für späteres Active Learning (initiell NULL)
+  "user_feedback"        TEXT,   -- NULL | "correct" | "false-positive" | "false-negative"
+  "feedback_at"          TIMESTAMPTZ,
+
+  "created_at"           TIMESTAMPTZ  NOT NULL DEFAULT NOW(),
+
+  CONSTRAINT "mail_classification_samples_pkey" PRIMARY KEY ("id")
+);
+
+-- Kern-Indizes
+CREATE INDEX "mail_classification_samples_user_idx"
+  ON "rebreak"."mail_classification_samples" ("user_id");
+
+CREATE INDEX "mail_classification_samples_created_idx"
+  ON "rebreak"."mail_classification_samples" ("created_at");
+
+-- Compound-Index für spätere Analyse-Queries
+-- z.B. "alle false-positives der letzten 30 Tage" oder "LLM-Block-Rate"
+CREATE INDEX "mail_classification_samples_action_trigger_idx"
+  ON "rebreak"."mail_classification_samples" ("final_action", "trigger_source");
+
+-- CHECK constraints für Datenqualität
+ALTER TABLE "rebreak"."mail_classification_samples"
+  ADD CONSTRAINT "mail_classification_samples_action_check"
+    CHECK ("final_action" IN ('blocked', 'passed'));
+
+-- Note: connection_id hat keinen FOREIGN KEY auf mail_connections, da die Connection
+-- vor dem Sample gelöscht werden kann (z.B. User disconnect). Nullable + orphan-safe.
diff --git a/backend/prisma/schema.prisma b/backend/prisma/schema.prisma
index 84090bf..841a922 100644
--- a/backend/prisma/schema.prisma
+++ b/backend/prisma/schema.prisma
@@ -638,6 +638,9 @@ model MailBlocked {
     subject        String
     receivedAt     DateTime @map("received_at")
     action         String
+    /// Welcher Layer die Blockierung ausgelöst hat (z.B. "domain", "brand+random", "score:85", "llm:0.92").
+    /// NULL für ältere Einträge (vor Migration 20260514).
+    triggerSource  String?  @map("trigger_source") @db.VarChar(64)
     createdAt      DateTime @default(now()) @map("created_at")
 
     connection MailConnection @relation(fields: [connectionId], references: [id], onDelete: Cascade)
@@ -647,6 +650,46 @@ model MailBlocked {
     @@schema("rebreak")
 }
 
+/// Klassifikations-Samples für ML-Phase 3 (zukünftiges Fine-Tuning / Modell-Evaluation).
+/// Enthält Features + Outcomes jeder Mail-Klassifikation.
+/// KEIN Mail-Body — nur Metadaten (Sender-Domain, Subject, Score-Komponenten).
+/// Cascade-Delete bei User-Löschung (Art. 17 DSGVO).
+model MailClassificationSample {
+    id                 String   @id @default(cuid())
+    userId             String   @map("user_id") @db.Uuid
+    connectionId       String?  @map("connection_id") @db.Uuid
+
+    // Raw features (was analysiert wurde):
+    senderName         String?  @map("sender_name") @db.VarChar(255)
+    senderDomain       String?  @map("sender_domain") @db.VarChar(255)
+    relayDecodedDomain String?  @map("relay_decoded_domain") @db.VarChar(255)
+    subject            String?  @db.VarChar(998) // RFC 5322 max
+
+    // Computed features (Score-Komponenten als JSON):
+    features           Json     // { score, brandMatch, randomTokens, keywordHits, styleFlags, … }
+
+    // Outcome:
+    finalAction        String   @map("final_action") // "blocked" | "passed"
+    triggerSource      String   @map("trigger_source") // "domain", "brand+random", "score:NN", "llm:0.XX", "whitelist"
+
+    // Groq verdict (nur wenn Layer 4 lief):
+    groqIsGambling     Boolean? @map("groq_is_gambling")
+    groqConfidence     Float?   @map("groq_confidence")
+    groqReason         String?  @map("groq_reason") @db.Text
+
+    // User-Feedback (für später):
+    userFeedback       String?  @map("user_feedback") // null | "correct" | "false-positive" | "false-negative"
+    feedbackAt         DateTime? @map("feedback_at")
+
+    createdAt          DateTime @default(now()) @map("created_at")
+
+    @@index([userId])
+    @@index([createdAt])
+    @@index([finalAction, triggerSource])
+    @@map("mail_classification_samples")
+    @@schema("rebreak")
+}
+
 /// Permanente Aggregat-Statistiken blockierter Mails pro Tag + Connection.
 /// Befüllt live beim Scan (vor dem 24h-Cleanup von mail_blocked).
 /// Enthält KEINE Mail-Inhalte — nur counts/dates (Datenminimierung Art. 5 DSGVO).
diff --git a/backend/server/api/mail/scan-internal.post.ts b/backend/server/api/mail/scan-internal.post.ts
index afacc6e..57fdea5 100644
--- a/backend/server/api/mail/scan-internal.post.ts
+++ b/backend/server/api/mail/scan-internal.post.ts
@@ -6,21 +6,22 @@ import {
   insertMailBlocked,
   upsertMailBlockedStat,
   updateMailConnectionScanStats,
+  insertMailClassificationSample,
 } from "../../db/mail";
 import { getBlocklistedDomainsSet } from "../../db/domains";
 import { getProfile } from "../../db/profile";
 import { getPlanLimits } from "../../utils/plan-features";
 import { resolveProviderMeta } from "../../utils/imap-providers";
 import { resolveImapAuth } from "../../utils/mail-auth";
-// Single-Source-of-Truth (Mo's Finding #4)
-// @ts-expect-error — .mjs ohne types, GAMBLING_KEYWORDS ist string[]
-import { GAMBLING_KEYWORDS } from "../../utils/gambling-keywords.mjs";
-
+import { classifyMail } from "../../utils/mail-classifier";
 
 /**
  * POST /api/mail/scan-internal
  * Called by cron or IMAP proxy. Scans ALL mailbox folders.
  * Free: only custom domains + keywords. Pro/Legend: global blocklist + custom.
+ *
+ * Klassifikations-Pipeline: Layer 0–4 via mail-classifier.ts.
+ * Layer 5 (Sample-Capture): nach jeder Klassifikation.
  */
 export default defineEventHandler(async (event) => {
   const secret = getHeader(event, "x-admin-secret");
@@ -44,7 +45,7 @@ export default defineEventHandler(async (event) => {
 
   if (skippedNoConsent > 0) {
     console.log(
-      `[scan-internal] skipping ${skippedNoConsent} connections for userId=${userId} — no consent_at (pending re-consent)`,
+      `[scan-internal] skipping ${skippedNoConsent} connections — no consent_at (pending re-consent)`,
     );
   }
 
@@ -53,8 +54,6 @@ export default defineEventHandler(async (event) => {
   }
 
   // Plan-aware blocklist
-  // Grace-Period: wenn globalBlocklistGraceUntil noch in der Zukunft liegt,
-  // behandeln wir den User als 'full' auch wenn sein Plan 'curated' sagt.
   const profile = await getProfile(userId);
   const limits = getPlanLimits(profile?.plan ?? "free");
   const inGrace =
@@ -64,20 +63,15 @@ export default defineEventHandler(async (event) => {
 
   await deleteOldMailBlocked(userId);
 
+  // Groq API Key aus runtimeConfig (Infisical-injiziert)
+  const config = useRuntimeConfig(event);
+  const groqApiKey: string = (config.groqApiKey as string) || process.env.GROQ_API_KEY || "";
+  const msClientId: string = (config.msOauthClientId as string) || process.env.MS_OAUTH_CLIENT_ID || "";
+
   let totalScanned = 0;
   let totalBlocked = 0;
 
-  // scan-internal läuft im Cron-Context (kein User-Event). useRuntimeConfig(event)
-  // funktioniert hier weil event die Admin-Auth-Request-Referenz ist. Falls der
-  // Daemon triggerScan() direkt ohne echten HTTP-Request aufruft, fällt der
-  // process.env-Fallback ein — beide Quellen zeigen auf dieselbe Azure Client-ID.
-  const config = useRuntimeConfig(event);
-  const msClientId: string = config.msOauthClientId as string || process.env.MS_OAUTH_CLIENT_ID || "";
-
   for (const connection of eligibleConnections) {
-    // resolveImapAuth() wählt automatisch den richtigen Auth-Pfad:
-    // oauth2_microsoft → Access-Token (mit proaktivem Refresh falls abgelaufen)
-    // alle anderen → App-Password decrypt
     let imapAuth: { user: string; accessToken: string } | { user: string; pass: string };
     try {
       imapAuth = await resolveImapAuth(connection, msClientId);
@@ -85,8 +79,6 @@ export default defineEventHandler(async (event) => {
       continue;
     }
 
-    // useStarttls=true → STARTTLS (secure=false + requireTLS=true)
-    // rejectUnauthorized=false → self-signed Certs zulassen (nur Custom-IMAP)
     const useImplicitTls = !connection.useStarttls;
     const imap = new ImapFlow({
       host: connection.imapHost,
@@ -104,7 +96,6 @@ export default defineEventHandler(async (event) => {
     try {
       await imap.connect();
 
-      // Scan ALL mailbox folders (not just hardcoded list)
       const mailboxes = await imap.list();
       const scannable = mailboxes.filter(
         (mb: any) => !mb.flags?.has("\\Noselect"),
@@ -137,24 +128,22 @@ export default defineEventHandler(async (event) => {
           const allUids = allMessages.map(
             (m: any) => `${mb.path}:${String(m.uid ?? m.seq)}`,
           );
+
+          // Alle Sender-Domains sammeln für Blocklist-Lookup
+          const senderDomains = allMessages
+            .map((m: any) =>
+              ((m.envelope?.from?.[0]?.address ?? "").toLowerCase().split("@")[1] ?? ""),
+            )
+            .filter(Boolean);
+
           const [blockedDomainSet, alreadyBlockedSet] = await Promise.all([
-            getBlocklistedDomainsSet(
-              allMessages
-                .map(
-                  (m: any) =>
-                    (m.envelope?.from?.[0]?.address ?? "")
-                      .toLowerCase()
-                      .split("@")[1] ?? "",
-                )
-                .filter(Boolean),
-              userId,
-              includeGlobal,
-            ),
+            getBlocklistedDomainsSet(senderDomains, userId, includeGlobal),
             getAlreadyBlockedUidSet(allUids, userId),
           ]);
 
           const toInsert: Parameters<typeof insertMailBlocked>[0] = [];
           const uidsToDelete: string[] = [];
+          const sampleInserts: Parameters<typeof insertMailClassificationSample>[0][] = [];
 
           for (const msg of allMessages) {
             const from = msg.envelope?.from?.[0];
@@ -164,18 +153,34 @@ export default defineEventHandler(async (event) => {
             const msgDate = msg.envelope?.date ?? new Date();
             const uid = `${mb.path}:${String(msg.uid ?? msg.seq)}`;
 
-            const haystack = `${senderEmail} ${subject}`.toLowerCase();
-            const isGamblingKeyword = GAMBLING_KEYWORDS.some((kw) =>
-              haystack.includes(kw),
-            );
-            const senderDomain = senderEmail.split("@")[1] ?? "";
-            const isBlocklisted = senderDomain
-              ? blockedDomainSet.has(senderDomain)
-              : false;
-
-            if (!isGamblingKeyword && !isBlocklisted) continue;
+            // Layer 0: Already blocked → skip, kein Sample
             if (alreadyBlockedSet.has(uid)) continue;
 
+            const result = await classifyMail({
+              mail: { senderEmail, senderName, subject },
+              blockedDomainSet,
+              groqApiKey,
+            });
+
+            // Layer 5: Sample-Capture (immer, außer Layer 0)
+            const senderDomain = senderEmail.split("@")[1] ?? null;
+            sampleInserts.push({
+              userId,
+              connectionId: connection.id,
+              senderName: senderName?.slice(0, 255) ?? null,
+              senderDomain: senderDomain?.slice(0, 255) ?? null,
+              relayDecodedDomain: result.relayDecodedDomain?.slice(0, 255) ?? null,
+              subject: subject.slice(0, 998) || null,
+              features: result.features as unknown as Record<string, unknown>,
+              finalAction: result.action,
+              triggerSource: result.triggerSource,
+              groqIsGambling: result.groq?.isGambling ?? null,
+              groqConfidence: result.groq?.confidence ?? null,
+              groqReason: result.groq?.reason ?? null,
+            });
+
+            if (result.action !== "blocked") continue;
+
             uidsToDelete.push(String(msg.uid));
             toInsert.push({
               userId,
@@ -186,6 +191,7 @@ export default defineEventHandler(async (event) => {
               subject: subject.slice(0, 200) || "(kein Betreff)",
               receivedAt: msgDate,
               action: "deleted",
+              triggerSource: result.triggerSource,
             });
             newlyBlocked++;
           }
@@ -212,7 +218,13 @@ export default defineEventHandler(async (event) => {
 
           await insertMailBlocked(toInsert);
 
-          // Aggregat-Stats aktualisieren (vor 24h-Cleanup resistent)
+          // Samples fire-and-forget (kein Scan-Result abhängig davon)
+          if (sampleInserts.length > 0) {
+            Promise.all(sampleInserts.map((s) => insertMailClassificationSample(s))).catch((err) => {
+              console.warn("[scan-internal] sample insert failed (non-fatal):", err);
+            });
+          }
+
           if (toInsert.length > 0) {
             const providerMeta = resolveProviderMeta(connection.imapHost);
             await upsertMailBlockedStat({
diff --git a/backend/server/api/mail/scan.post.ts b/backend/server/api/mail/scan.post.ts
index b031f23..f5bade4 100644
--- a/backend/server/api/mail/scan.post.ts
+++ b/backend/server/api/mail/scan.post.ts
@@ -6,21 +6,22 @@ import {
   insertMailBlocked,
   upsertMailBlockedStat,
   updateMailConnectionScanStats,
+  insertMailClassificationSample,
 } from "../../db/mail";
 import { getBlocklistedDomainsSet } from "../../db/domains";
 import { getProfile } from "../../db/profile";
 import { getPlanLimits } from "../../utils/plan-features";
 import { resolveProviderMeta } from "../../utils/imap-providers";
 import { resolveImapAuth } from "../../utils/mail-auth";
-// Single-Source-of-Truth (Mo's Finding #4)
-// @ts-expect-error — .mjs ohne types, GAMBLING_KEYWORDS ist string[]
-import { GAMBLING_KEYWORDS } from "../../utils/gambling-keywords.mjs";
-
+import { classifyMail } from "../../utils/mail-classifier";
 
 /**
  * POST /api/mail/scan
  * Scannt ALLE Ordner (INBOX, Spam, Papierkorb, All Mail …) nach Gambling-Mails.
  * Free-User: nur eigene Domains + Keywords. Pro/Legend: globale Blocklist + eigene.
+ *
+ * Klassifikations-Pipeline: Layer 0–4 via mail-classifier.ts.
+ * Layer 5 (Sample-Capture): nach jeder Klassifikation.
  */
 export default defineEventHandler(async (event) => {
   const user = await requireUser(event);
@@ -46,7 +47,6 @@ export default defineEventHandler(async (event) => {
   // Plan-aware: Free users get only custom domains, Pro/Legend get global blocklist
   const profile = await getProfile(user.id);
   const limits = getPlanLimits(profile?.plan ?? "free");
-  // Grace-Period berücksichtigen
   const inGrace =
     profile?.globalBlocklistGraceUntil != null &&
     new Date(profile.globalBlocklistGraceUntil) > new Date();
@@ -54,16 +54,14 @@ export default defineEventHandler(async (event) => {
 
   await deleteOldMailBlocked(user.id);
 
+  const config = useRuntimeConfig(event);
+  const groqApiKey: string = (config.groqApiKey as string) || process.env.GROQ_API_KEY || "";
+  const msClientId: string = (config.msOauthClientId as string) || process.env.MS_OAUTH_CLIENT_ID || "";
+
   let totalScanned = 0;
   let totalBlocked = 0;
 
-  const config = useRuntimeConfig(event);
-  const msClientId: string = config.msOauthClientId as string || process.env.MS_OAUTH_CLIENT_ID || "";
-
   for (const connection of eligibleConnections) {
-    // resolveImapAuth() wählt automatisch den richtigen Auth-Pfad:
-    // oauth2_microsoft → Access-Token (mit proaktivem Refresh falls abgelaufen)
-    // alle anderen → App-Password decrypt
     let imapAuth: { user: string; accessToken: string } | { user: string; pass: string };
     try {
       imapAuth = await resolveImapAuth(connection, msClientId);
@@ -71,8 +69,6 @@ export default defineEventHandler(async (event) => {
       continue;
     }
 
-    // useStarttls=true → STARTTLS (secure=false + requireTLS=true)
-    // rejectUnauthorized=false → self-signed Certs zulassen (nur Custom-IMAP)
     const useImplicitTls = !connection.useStarttls;
     const imap = new ImapFlow({
       host: connection.imapHost,
@@ -90,7 +86,6 @@ export default defineEventHandler(async (event) => {
     try {
       await imap.connect();
 
-      // Scan ALL mailbox folders (not just hardcoded list)
       const mailboxes = await imap.list();
       const scannable = mailboxes.filter(
         (mb: any) => !mb.flags?.has("\\Noselect"),
@@ -120,24 +115,21 @@ export default defineEventHandler(async (event) => {
           const allUids = allMessages.map(
             (m: any) => `${mb.path}:${String(m.uid ?? m.seq)}`,
           );
+
+          const senderDomains = allMessages
+            .map((m: any) =>
+              ((m.envelope?.from?.[0]?.address ?? "").toLowerCase().split("@")[1] ?? ""),
+            )
+            .filter(Boolean);
+
           const [blockedDomainSet, alreadyBlockedSet] = await Promise.all([
-            getBlocklistedDomainsSet(
-              allMessages
-                .map(
-                  (m: any) =>
-                    (m.envelope?.from?.[0]?.address ?? "")
-                      .toLowerCase()
-                      .split("@")[1] ?? "",
-                )
-                .filter(Boolean),
-              user.id,
-              includeGlobal,
-            ),
+            getBlocklistedDomainsSet(senderDomains, user.id, includeGlobal),
             getAlreadyBlockedUidSet(allUids, user.id),
           ]);
 
           const toInsert: Parameters<typeof insertMailBlocked>[0] = [];
           const uidsToDelete: string[] = [];
+          const sampleInserts: Parameters<typeof insertMailClassificationSample>[0][] = [];
 
           for (const msg of allMessages) {
             const from = msg.envelope?.from?.[0];
@@ -147,18 +139,34 @@ export default defineEventHandler(async (event) => {
             const msgDate = msg.envelope?.date ?? new Date();
             const uid = `${mb.path}:${String(msg.uid ?? msg.seq)}`;
 
-            const haystack = `${senderEmail} ${subject}`.toLowerCase();
-            const isGamblingKeyword = GAMBLING_KEYWORDS.some((kw) =>
-              haystack.includes(kw),
-            );
-            const senderDomain = senderEmail.split("@")[1] ?? "";
-            const isBlocklisted = senderDomain
-              ? blockedDomainSet.has(senderDomain)
-              : false;
-
-            if (!isGamblingKeyword && !isBlocklisted) continue;
+            // Layer 0: Already blocked → skip, kein Sample
             if (alreadyBlockedSet.has(uid)) continue;
 
+            const result = await classifyMail({
+              mail: { senderEmail, senderName, subject },
+              blockedDomainSet,
+              groqApiKey,
+            });
+
+            // Layer 5: Sample-Capture (immer, außer Layer 0)
+            const senderDomain = senderEmail.split("@")[1] ?? null;
+            sampleInserts.push({
+              userId: user.id,
+              connectionId: connection.id,
+              senderName: senderName?.slice(0, 255) ?? null,
+              senderDomain: senderDomain?.slice(0, 255) ?? null,
+              relayDecodedDomain: result.relayDecodedDomain?.slice(0, 255) ?? null,
+              subject: subject.slice(0, 998) || null,
+              features: result.features as unknown as Record<string, unknown>,
+              finalAction: result.action,
+              triggerSource: result.triggerSource,
+              groqIsGambling: result.groq?.isGambling ?? null,
+              groqConfidence: result.groq?.confidence ?? null,
+              groqReason: result.groq?.reason ?? null,
+            });
+
+            if (result.action !== "blocked") continue;
+
             uidsToDelete.push(String(msg.uid));
             toInsert.push({
               userId: user.id,
@@ -169,11 +177,11 @@ export default defineEventHandler(async (event) => {
               subject: subject.slice(0, 200) || "(kein Betreff)",
               receivedAt: msgDate,
               action: "deleted",
+              triggerSource: result.triggerSource,
             });
             newlyBlocked++;
           }
 
-          // Permanently delete gambling mails from this folder
           if (uidsToDelete.length > 0) {
             try {
               await imap.messageDelete(uidsToDelete.join(","), { uid: true });
@@ -193,7 +201,13 @@ export default defineEventHandler(async (event) => {
 
           await insertMailBlocked(toInsert);
 
-          // Aggregat-Stats aktualisieren (vor 24h-Cleanup resistent)
+          // Samples fire-and-forget
+          if (sampleInserts.length > 0) {
+            Promise.all(sampleInserts.map((s) => insertMailClassificationSample(s))).catch((err) => {
+              console.warn("[scan] sample insert failed (non-fatal):", err);
+            });
+          }
+
           if (toInsert.length > 0) {
             const providerMeta = resolveProviderMeta(connection.imapHost);
             await upsertMailBlockedStat({
diff --git a/backend/server/db/mail.ts b/backend/server/db/mail.ts
index 3b9b3a4..c2d9004 100644
--- a/backend/server/db/mail.ts
+++ b/backend/server/db/mail.ts
@@ -183,6 +183,7 @@ export async function insertMailBlocked(
     subject: string;
     receivedAt: Date;
     action: string;
+    triggerSource?: string | null;
   }[],
 ) {
   if (entries.length === 0) return;
@@ -190,6 +191,42 @@ export async function insertMailBlocked(
   await db.mailBlocked.createMany({ data: entries, skipDuplicates: true });
 }
 
+// ─── MailClassificationSample ─────────────────────────────────────────────────
+
+/**
+ * Schreibt einen Klassifikations-Sample-Eintrag für ML-Phase 3.
+ * Wird nach JEDER Klassifikation aufgerufen (außer Layer 0 / Already-blocked Skips).
+ *
+ * DSGVO: Nur Features, keine Mail-Inhalte (kein Body). Subject + Sender sind
+ * kurzlebige Detection-Signale, kein narrativer Inhalt. Cascade-Delete bei
+ * User-Löschung (Art. 17).
+ */
+export async function insertMailClassificationSample(entry: {
+  userId: string;
+  connectionId: string | null;
+  senderName: string | null;
+  senderDomain: string | null;
+  relayDecodedDomain: string | null;
+  subject: string | null;
+  // features ist ein Prisma-Json-Feld — InputJsonValue erwartet kein plain Record.
+  // Wir serialisieren explizit via JSON.parse(JSON.stringify(...)) für TS-Zufriedenheit.
+  features: Record<string, unknown>;
+  finalAction: string;
+  triggerSource: string;
+  groqIsGambling?: boolean | null;
+  groqConfidence?: number | null;
+  groqReason?: string | null;
+}) {
+  const db = usePrisma();
+  // JSON.parse(JSON.stringify(features)) liefert ein "plain JSON value" das Prisma akzeptiert.
+  // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+  const featuresJson = JSON.parse(JSON.stringify(entry.features));
+  await db.mailClassificationSample.create({
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+    data: { ...entry, features: featuresJson },
+  });
+}
+
 /**
  * Gibt alle MailConnections eines Users zurück bei denen consent_at noch NULL ist.
  * Wird vom pending-consent.get.ts Endpoint für den Re-Consent-Modal-Trigger genutzt.
diff --git a/backend/server/utils/mail-classifier.ts b/backend/server/utils/mail-classifier.ts
new file mode 100644
index 0000000..b4f21af
--- /dev/null
+++ b/backend/server/utils/mail-classifier.ts
@@ -0,0 +1,657 @@
+/**
+ * Mail-Klassifikations-Pipeline (Layer 0–4 + Sample-Capture).
+ *
+ * Architektur:
+ *   Layer 0   — Skip-Guard (bereits geblockt / kein Consent)
+ *   Layer 1   — Whitelist (wetter, wettkampf …) → PASS
+ *   Layer 2   — Domain-Hard-Block (Blocklist)
+ *   Layer 2.5 — Brand+Random-Token-Detection (Hard-Block ohne LLM)
+ *   Layer 3   — Score 0–100 (deterministisch)
+ *   Layer 4   — Groq-Borderline (Score 25–75, mit Local-Part-Redact)
+ *   Layer 5   — MailClassificationSample-Insert (immer, außer Layer 0)
+ *
+ * Alle Layer-Logiken sind pure Funktionen → vollständig unit-testbar ohne DB-Mocks.
+ *
+ * DSGVO-Hinweise:
+ *   - Mail-Inhalte (Body) werden nie persistiert (Art. 9).
+ *   - Local-Part der Sender-Adresse wird vor dem Groq-Call redacted
+ *     (es sei denn, er enthält selbst Casino-Keywords — dann ist er Detection-Signal).
+ *   - userId in Logs nur wenn absolut nötig (Datenminimierung Art. 5).
+ *   - MailClassificationSample: Cascade-Delete via userId-Relation (Art. 17).
+ */
+
+// eslint-disable-next-line @typescript-eslint/ban-ts-comment
+// @ts-ignore — .mjs ohne types, Exports sind string[]
+import { GAMBLING_KEYWORDS, GAMBLING_WHITELIST } from "./gambling-keywords.mjs";
+
+// ─── Typen ─────────────────────────────────────────────────────────────────────
+
+export type ClassificationAction = "blocked" | "passed";
+
+export type TriggerSource =
+  | "domain"
+  | "relay-decoded"
+  | "brand+random"
+  | `score:${number}`
+  | `llm:${string}`
+  | "whitelist"
+  | "no-signal";
+
+export interface MailInput {
+  /** Sender-E-Mail-Adresse (lowercase, wie von IMAP geliefert) */
+  senderEmail: string;
+  /** Display-Name des Absenders (kann leer sein) */
+  senderName: string | null;
+  /** Betreff-Zeile */
+  subject: string;
+}
+
+export interface ClassificationResult {
+  action: ClassificationAction;
+  triggerSource: TriggerSource;
+  score: number;
+  /** Aus Relay-Adressen extrahierte echte Domain (z.B. gamblezen.com) */
+  relayDecodedDomain: string | null;
+  /** Groq-Verdict (nur wenn Layer 4 lief) */
+  groq?: {
+    isGambling: boolean;
+    confidence: number;
+    reason: string;
+  };
+  /** Score-Komponenten für MailClassificationSample.features */
+  features: ClassificationFeatures;
+}
+
+export interface ClassificationFeatures {
+  score: number;
+  domainBlocked: boolean;
+  relayDecoded: boolean;
+  brandMatch: boolean;
+  randomTokens: boolean;
+  keywordHitsSubject: string[];
+  keywordHitsDomain: string[];
+  keywordHitsName: string[];
+  styleFlags: string[];
+  whitelistHit: boolean;
+}
+
+// ─── Score-Weights (TS-Constants, kein Config-File-Overhead) ──────────────────
+
+export const SCORE_WEIGHTS = {
+  // Domain-Indikatoren
+  DOMAIN_GAMBLING_KEYWORD: 40,    // Domain enthält Gambling-Begriff (bet, casino, slots …)
+  DOMAIN_SHORT_RANDOM: 15,        // Domain-Root < 6 Zeichen und zufällig wirkend (betx, 1win)
+
+  // Subject-Indikatoren
+  SUBJECT_GAMBLING_KEYWORD: 35,   // Keyword im Betreff (casino, jackpot, freispiel …)
+  SUBJECT_MONEY_PATTERN: 20,      // €/$ + Zahl (z.B. "100€ Bonus")
+  SUBJECT_URGENCY: 15,            // "Nur heute", "Letzte Chance", "Ablaufdatum"
+  SUBJECT_ALL_CAPS_WORD: 5,       // EINZELNES ALL-CAPS-WORT im Betreff
+
+  // Display-Name-Indikatoren
+  SENDER_NAME_GAMBLING_KEYWORD: 30, // Gambling-Begriff im Absender-Namen
+  SENDER_NAME_BRAND_MATCH: 20,      // Name matcht bekannten Gambling-Brand (normalisiert)
+
+  // Layer 2.5 Score-Ergänzungen (wenn kein Hard-Block ausgelöst)
+  BRAND_MATCH_NO_RANDOM: 35,      // Brand-Match ohne Random-Tokens (kein Hard-Block)
+  RANDOM_TOKENS_NO_BRAND: 10,     // Random-Tokens ohne Brand-Match
+} as const;
+
+// Hard-Block-Threshold: Score >= 80 → BLOCK ohne LLM
+const SCORE_HARD_BLOCK_THRESHOLD = 80;
+// Borderline-Range: 25–75 → Groq-Call
+const SCORE_BORDERLINE_LOW = 25;
+const SCORE_BORDERLINE_HIGH = 75;
+
+// ─── Bekannte Gambling-Brands (für Brand-Match-Normalisierung) ─────────────────
+// Abgeleitet aus GAMBLING_KEYWORDS + typischen Blocklist-Domains.
+// Normalisierungsregel: lowercase, alle Sonder- und Leerzeichen entfernt.
+const GAMBLING_BRANDS: string[] = [
+  "casino", "bet365", "bwin", "tipico", "unibet", "betway", "888casino",
+  "pokerstars", "interwetten", "netbet", "leovegas", "mrgreen",
+  "betsson", "neobet", "mybet", "lottoland", "betano", "williamhill",
+  "paddypower", "betfair", "stake", "rolletto", "vbet", "1xbet", "melbet",
+  "mostbet", "luckyvibe", "spinz", "casinoly", "rabona",
+  "justcasino", "getslots", "rocketplay", "freshcasino",
+  "nomnomcasino", "gamblezen", "betandplay",
+];
+
+// ─── Relay-Decoder ─────────────────────────────────────────────────────────────
+
+/**
+ * Extrahiert die echte Ziel-Domain aus einer E-Mail-Relay-Adresse.
+ *
+ * Muster die wir kennen:
+ *   bounces+user=example.com@sendgrid.net    → example.com
+ *   track.user=gamblezen.com@mailchimp.com   → gamblezen.com
+ *   a1b2c3_user_at_betandplay.com@em.em.xyz  → betandplay.com
+ *   user=betandplay.com@bounce.em.example    → betandplay.com
+ *
+ * Pattern: Sucht nach `=domain.tld` oder `_at_domain.tld` im local-part.
+ */
+export function extractRelayedDomain(senderEmail: string): string | null {
+  if (!senderEmail.includes("@")) return null;
+  const [localPart] = senderEmail.split("@");
+
+  // Pattern 1: user=domain.tld (SendGrid, Mailchimp, SES-Bounces)
+  const eqMatch = localPart.match(/=([a-z0-9][\w-]*\.[a-z]{2,}(?:\.[a-z]{2,})?)(?:[+_&]|$)/i);
+  if (eqMatch) return eqMatch[1].toLowerCase();
+
+  // Pattern 2: _at_domain.tld (weniger häufig, einige Custom-Relay-Setups)
+  const atMatch = localPart.match(/_at_([a-z0-9][\w-]*\.[a-z]{2,}(?:\.[a-z]{2,})?)(?:[_+]|$)/i);
+  if (atMatch) return atMatch[1].toLowerCase();
+
+  return null;
+}
+
+// ─── Brand-Normalisierung ──────────────────────────────────────────────────────
+
+/**
+ * Normalisiert einen String für Brand-Vergleiche.
+ * "BetandPlay" → "betandplay", "bet-and-play.com" → "betandplay" (nach Strip)
+ */
+export function normalizeBrand(s: string): string {
+  return s.toLowerCase().replace(/[\s\-._]/g, "");
+}
+
+/**
+ * Prüft ob ein normalisierter String mit einem bekannten Gambling-Brand übereinstimmt.
+ * Mindestlänge 4 Zeichen um False-Positives zu vermeiden ("bet" alleine → zu kurz).
+ */
+export function matchesGamblingBrand(normalized: string): boolean {
+  if (normalized.length < 4) return false;
+  return GAMBLING_BRANDS.some((brand) => normalized === brand || normalized.includes(brand));
+}
+
+/**
+ * Extrahiert Brand-Kandidaten aus einer Domain für den Match-Check.
+ * "betand-play.com" → ["betandplay", "betand"] (root + normalisiert)
+ */
+function domainToBrandCandidates(domain: string): string[] {
+  const root = domain.split(".")[0] ?? "";
+  return [normalizeBrand(root), normalizeBrand(domain)];
+}
+
+// ─── Random-Token-Detection ───────────────────────────────────────────────────
+
+/**
+ * Erkennt zufällig wirkende Tokens im Local-Part einer E-Mail-Adresse.
+ *
+ * Definition "random token": >= 6 Zeichen, Mix aus Buchstaben + Ziffern,
+ * kein bekanntes Funktions-Wort (info, admin, noreply, support …).
+ *
+ * Ein Local-Part mit >= 2 solchen Tokens gilt als "random-looking" —
+ * typisch für Massen-Mailer mit trackierbaren User-IDs.
+ */
+export function hasRandomTokens(localPart: string): boolean {
+  const FUNCTION_WORDS = new Set([
+    "info", "admin", "noreply", "no-reply", "support", "hello",
+    "news", "marketing", "sales", "contact", "newsletter", "service",
+    "offers", "promotions", "promo", "team", "mail", "email",
+    "reply", "bounce", "return", "postmaster", "mailer",
+  ]);
+
+  const tokens = localPart.split(/[_\-.+]+/);
+  const randomLooking = tokens.filter((t) => {
+    if (t.length < 6) return false;
+    if (!/[a-z]/i.test(t) || !/[0-9]/.test(t)) return false; // muss Letters+Digits haben
+    const lower = t.toLowerCase();
+    if (FUNCTION_WORDS.has(lower)) return false;
+    return true;
+  });
+
+  return randomLooking.length >= 2;
+}
+
+// ─── Local-Part-Redaction ─────────────────────────────────────────────────────
+
+/**
+ * Redacted den Local-Part einer E-Mail-Adresse vor dem Groq-Call (DSGVO).
+ *
+ * AUSNAHME: wenn der Local-Part selbst Gambling-Keywords enthält
+ * (z.B. "casino_offers_abc123@mailer.com"), bleibt er erhalten —
+ * er ist in diesem Fall ein Klassifikations-Signal, kein PII.
+ */
+export function redactLocalPartForLLM(
+  senderEmail: string,
+  localPartHasKeyword: boolean,
+): string {
+  if (localPartHasKeyword) return senderEmail;
+  const atIdx = senderEmail.indexOf("@");
+  if (atIdx === -1) return senderEmail;
+  return `***${senderEmail.slice(atIdx)}`;
+}
+
+// ─── Score-Berechnung (Layer 3) ───────────────────────────────────────────────
+
+interface ScoreResult {
+  score: number;
+  keywordHitsSubject: string[];
+  keywordHitsDomain: string[];
+  keywordHitsName: string[];
+  styleFlags: string[];
+  whitelistHit: boolean;
+}
+
+export function computeScore(
+  senderEmail: string,
+  senderName: string | null,
+  subject: string,
+  brandMatchFound: boolean,
+  randomTokensFound: boolean,
+): ScoreResult {
+  let score = 0;
+  const keywordHitsSubject: string[] = [];
+  const keywordHitsDomain: string[] = [];
+  const keywordHitsName: string[] = [];
+  const styleFlags: string[] = [];
+
+  const subjectLower = subject.toLowerCase();
+  const senderEmailLower = senderEmail.toLowerCase();
+  const senderNameLower = (senderName ?? "").toLowerCase();
+  const domain = senderEmailLower.split("@")[1] ?? "";
+  const domainRoot = domain.split(".")[0] ?? "";
+
+  // ── Whitelist-Check (Layer 1) ──
+  for (const w of GAMBLING_WHITELIST as string[]) {
+    if (subjectLower.includes(w) || senderEmailLower.includes(w) || senderNameLower.includes(w)) {
+      return {
+        score: 0,
+        keywordHitsSubject: [],
+        keywordHitsDomain: [],
+        keywordHitsName: [],
+        styleFlags: [],
+        whitelistHit: true,
+      };
+    }
+  }
+
+  // ── Domain-Keywords ──
+  for (const kw of GAMBLING_KEYWORDS as string[]) {
+    if (domain.includes(kw) || domainRoot.includes(kw)) {
+      keywordHitsDomain.push(kw);
+      score += SCORE_WEIGHTS.DOMAIN_GAMBLING_KEYWORD;
+      break; // einmal reicht
+    }
+  }
+
+  // ── Subject-Keywords ──
+  for (const kw of GAMBLING_KEYWORDS as string[]) {
+    if (subjectLower.includes(kw)) {
+      keywordHitsSubject.push(kw);
+      score += SCORE_WEIGHTS.SUBJECT_GAMBLING_KEYWORD;
+      break;
+    }
+  }
+
+  // ── Sender-Name-Keywords ──
+  for (const kw of GAMBLING_KEYWORDS as string[]) {
+    if (senderNameLower.includes(kw)) {
+      keywordHitsName.push(kw);
+      score += SCORE_WEIGHTS.SENDER_NAME_GAMBLING_KEYWORD;
+      break;
+    }
+  }
+
+  // ── Geld-Pattern im Betreff (€/$ + Zahl) ──
+  if (/[€$£]\s*\d|\d\s*[€$£]/.test(subject)) {
+    styleFlags.push("money-pattern");
+    score += SCORE_WEIGHTS.SUBJECT_MONEY_PATTERN;
+  }
+
+  // ── Urgency-Wörter im Betreff ──
+  const URGENCY_PATTERNS = [
+    "nur heute", "letzte chance", "läuft ab", "ablaufdatum",
+    "expires", "last chance", "limited time", "jetzt einlösen",
+    "sofort", "nur noch", "endet heute",
+  ];
+  if (URGENCY_PATTERNS.some((p) => subjectLower.includes(p))) {
+    styleFlags.push("urgency");
+    score += SCORE_WEIGHTS.SUBJECT_URGENCY;
+  }
+
+  // ── ALL-CAPS-Wort im Betreff ──
+  if (/\b[A-Z]{4,}\b/.test(subject)) {
+    styleFlags.push("all-caps");
+    score += SCORE_WEIGHTS.SUBJECT_ALL_CAPS_WORD;
+  }
+
+  // ── Short-Random-Domain ──
+  if (domainRoot.length > 0 && domainRoot.length <= 5 && /[a-z]/.test(domainRoot) && /[0-9]/.test(domainRoot)) {
+    styleFlags.push("short-random-domain");
+    score += SCORE_WEIGHTS.DOMAIN_SHORT_RANDOM;
+  }
+
+  // ── Layer 2.5 Score-Ergänzungen ──
+  if (brandMatchFound && !randomTokensFound) {
+    score += SCORE_WEIGHTS.BRAND_MATCH_NO_RANDOM;
+  }
+  if (!brandMatchFound && randomTokensFound) {
+    score += SCORE_WEIGHTS.RANDOM_TOKENS_NO_BRAND;
+  }
+
+  return {
+    score: Math.min(score, 100),
+    keywordHitsSubject,
+    keywordHitsDomain,
+    keywordHitsName,
+    styleFlags,
+    whitelistHit: false,
+  };
+}
+
+// ─── Groq-LLM-Call (Layer 4) ─────────────────────────────────────────────────
+
+interface GroqVerdict {
+  isGambling: boolean;
+  confidence: number;
+  reason: string;
+}
+
+/**
+ * Ruft Groq Llama 3.3 70B zur Borderline-Klassifikation auf.
+ * Sendet NUR: senderName, senderEmail (ggf. local-part-redacted), subject.
+ * KEIN Mail-Body, KEINE weiteren PII.
+ */
+export async function callGroqClassifier(params: {
+  senderName: string | null;
+  senderEmailRedacted: string;
+  subject: string;
+  groqApiKey: string;
+}): Promise<GroqVerdict> {
+  const prompt = `You are a spam classifier for a gambling addiction recovery app.
+Classify whether this email is from a gambling/betting operator.
+
+Sender name: ${params.senderName ?? "(none)"}
+Sender email: ${params.senderEmailRedacted}
+Subject: ${params.subject}
+
+Respond with ONLY valid JSON in this exact format:
+{"isGambling": true/false, "confidence": 0.0-1.0, "reason": "one sentence"}
+
+Do not include any other text.`;
+
+  const response = await fetch("https://api.groq.com/openai/v1/chat/completions", {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/json",
+      Authorization: `Bearer ${params.groqApiKey}`,
+    },
+    body: JSON.stringify({
+      model: "llama-3.3-70b-versatile",
+      messages: [{ role: "user", content: prompt }],
+      temperature: 0,
+      max_tokens: 100,
+      response_format: { type: "json_object" },
+    }),
+  });
+
+  if (!response.ok) {
+    const errText = await response.text().catch(() => "");
+    throw new Error(`Groq API error ${response.status}: ${errText.slice(0, 200)}`);
+  }
+
+  const data = await response.json() as {
+    choices: { message: { content: string } }[];
+  };
+
+  const raw = data.choices?.[0]?.message?.content ?? "{}";
+
+  try {
+    const parsed = JSON.parse(raw) as Partial<GroqVerdict>;
+    return {
+      isGambling: Boolean(parsed.isGambling),
+      confidence: typeof parsed.confidence === "number" ? parsed.confidence : 0,
+      reason: typeof parsed.reason === "string" ? parsed.reason.slice(0, 300) : "",
+    };
+  } catch {
+    // JSON-Parse-Fehler → konservativ PASS (kein false-positive durch LLM-Fehler)
+    return { isGambling: false, confidence: 0, reason: "parse-error" };
+  }
+}
+
+// ─── Haupt-Pipeline ───────────────────────────────────────────────────────────
+
+export interface ClassifyMailParams {
+  mail: MailInput;
+  /** Menge der geblockten Domains (aus getBlocklistedDomainsSet) */
+  blockedDomainSet: Set<string>;
+  /** Groq API Key (aus runtimeConfig) — wenn leer, Layer 4 überspringen */
+  groqApiKey: string;
+}
+
+/**
+ * Klassifiziert eine einzelne Mail durch alle Layer.
+ * Pure bezüglich IO — Groq-Call ist die einzige externe Abhängigkeit.
+ * DB-Writes (MailBlocked, MailClassificationSample) liegen beim Aufrufer.
+ */
+export async function classifyMail(params: ClassifyMailParams): Promise<ClassificationResult> {
+  const { mail, blockedDomainSet, groqApiKey } = params;
+  const { senderEmail, senderName, subject } = mail;
+
+  const senderEmailLower = senderEmail.toLowerCase();
+  const domain = senderEmailLower.split("@")[1] ?? "";
+  const localPart = senderEmailLower.split("@")[0] ?? "";
+
+  // ── Layer 1: Whitelist ──────────────────────────────────────────────────────
+  const haystack = `${senderEmailLower} ${subject} ${senderName ?? ""}`.toLowerCase();
+  for (const w of GAMBLING_WHITELIST as string[]) {
+    if (haystack.includes(w)) {
+      return {
+        action: "passed",
+        triggerSource: "whitelist",
+        score: 0,
+        relayDecodedDomain: null,
+        features: {
+          score: 0,
+          domainBlocked: false,
+          relayDecoded: false,
+          brandMatch: false,
+          randomTokens: false,
+          keywordHitsSubject: [],
+          keywordHitsDomain: [],
+          keywordHitsName: [],
+          styleFlags: [],
+          whitelistHit: true,
+        },
+      };
+    }
+  }
+
+  // ── Layer 2: Domain-Hard-Block ──────────────────────────────────────────────
+  if (domain && blockedDomainSet.has(domain)) {
+    return {
+      action: "blocked",
+      triggerSource: "domain",
+      score: 100,
+      relayDecodedDomain: null,
+      features: {
+        score: 100,
+        domainBlocked: true,
+        relayDecoded: false,
+        brandMatch: false,
+        randomTokens: false,
+        keywordHitsSubject: [],
+        keywordHitsDomain: [],
+        keywordHitsName: [],
+        styleFlags: [],
+        whitelistHit: false,
+      },
+    };
+  }
+
+  // ── Layer 2: Relay-Decoded Domain-Block ─────────────────────────────────────
+  const relayDecodedDomain = extractRelayedDomain(senderEmailLower);
+  if (relayDecodedDomain && blockedDomainSet.has(relayDecodedDomain)) {
+    return {
+      action: "blocked",
+      triggerSource: "relay-decoded",
+      score: 100,
+      relayDecodedDomain,
+      features: {
+        score: 100,
+        domainBlocked: false,
+        relayDecoded: true,
+        brandMatch: false,
+        randomTokens: false,
+        keywordHitsSubject: [],
+        keywordHitsDomain: [],
+        keywordHitsName: [],
+        styleFlags: [],
+        whitelistHit: false,
+      },
+    };
+  }
+
+  // ── Layer 2.5: Brand+Random-Token-Hard-Block ────────────────────────────────
+  // Normalisiere Absender-Name und Domain-Root für Brand-Vergleich
+  const displayNameNorm = normalizeBrand(senderName ?? "");
+  const domainCandidates = domainToBrandCandidates(domain);
+  const relayDomainCandidates = relayDecodedDomain ? domainToBrandCandidates(relayDecodedDomain) : [];
+  const allBrandCandidates = [displayNameNorm, ...domainCandidates, ...relayDomainCandidates];
+
+  const brandMatch = allBrandCandidates.some((c) => c.length >= 4 && matchesGamblingBrand(c));
+  const randomTokens = hasRandomTokens(localPart);
+
+  if (brandMatch && randomTokens) {
+    return {
+      action: "blocked",
+      triggerSource: "brand+random",
+      score: 100,
+      relayDecodedDomain,
+      features: {
+        score: 100,
+        domainBlocked: false,
+        relayDecoded: !!relayDecodedDomain,
+        brandMatch: true,
+        randomTokens: true,
+        keywordHitsSubject: [],
+        keywordHitsDomain: [],
+        keywordHitsName: [],
+        styleFlags: [],
+        whitelistHit: false,
+      },
+    };
+  }
+
+  // ── Layer 3: Score ──────────────────────────────────────────────────────────
+  const scoreResult = computeScore(
+    senderEmailLower,
+    senderName,
+    subject,
+    brandMatch,
+    randomTokens,
+  );
+
+  if (scoreResult.whitelistHit) {
+    return {
+      action: "passed",
+      triggerSource: "whitelist",
+      score: 0,
+      relayDecodedDomain,
+      features: {
+        ...scoreResult,
+        score: 0,
+        domainBlocked: false,
+        relayDecoded: !!relayDecodedDomain,
+        brandMatch,
+        randomTokens,
+      },
+    };
+  }
+
+  const score = scoreResult.score;
+
+  // Score >= 80 → Hard-Block, kein LLM
+  if (score >= SCORE_HARD_BLOCK_THRESHOLD) {
+    const triggerSource: TriggerSource = `score:${score}`;
+    return {
+      action: "blocked",
+      triggerSource,
+      score,
+      relayDecodedDomain,
+      features: {
+        ...scoreResult,
+        domainBlocked: false,
+        relayDecoded: !!relayDecodedDomain,
+        brandMatch,
+        randomTokens,
+      },
+    };
+  }
+
+  // Score < 25 → PASS, kein LLM
+  if (score < SCORE_BORDERLINE_LOW) {
+    return {
+      action: "passed",
+      triggerSource: "no-signal",
+      score,
+      relayDecodedDomain,
+      features: {
+        ...scoreResult,
+        domainBlocked: false,
+        relayDecoded: !!relayDecodedDomain,
+        brandMatch,
+        randomTokens,
+      },
+    };
+  }
+
+  // ── Layer 4: Groq-Borderline (25–75) ────────────────────────────────────────
+  if (score >= SCORE_BORDERLINE_LOW && score <= SCORE_BORDERLINE_HIGH && groqApiKey) {
+    // Local-Part-Redaction: nur behalten wenn er selbst Gambling-Keywords enthält
+    const localPartHasKeyword = (GAMBLING_KEYWORDS as string[]).some((kw: string) =>
+      localPart.toLowerCase().includes(kw),
+    );
+    const senderEmailRedacted = redactLocalPartForLLM(senderEmailLower, localPartHasKeyword);
+
+    let groqVerdict: GroqVerdict | null = null;
+    try {
+      groqVerdict = await callGroqClassifier({
+        senderName,
+        senderEmailRedacted,
+        subject,
+        groqApiKey,
+      });
+    } catch (err) {
+      // LLM-Fehler → konservativ PASS (kein false-positive durch API-Ausfall)
+      console.warn("[mail-classifier] Groq call failed, falling back to score-based decision:", err);
+    }
+
+    if (groqVerdict) {
+      const action: ClassificationAction = groqVerdict.isGambling ? "blocked" : "passed";
+      const triggerSource: TriggerSource = `llm:${groqVerdict.confidence.toFixed(2)}`;
+      return {
+        action,
+        triggerSource,
+        score,
+        relayDecodedDomain,
+        groq: groqVerdict,
+        features: {
+          ...scoreResult,
+          domainBlocked: false,
+          relayDecoded: !!relayDecodedDomain,
+          brandMatch,
+          randomTokens,
+        },
+      };
+    }
+  }
+
+  // Fallback: Score 25–75 ohne Groq (API-Fehler oder kein Key) → PASS bei < 50, BLOCK bei >= 50
+  const fallbackAction: ClassificationAction = score >= 50 ? "blocked" : "passed";
+  const fallbackTrigger: TriggerSource = `score:${score}`;
+  return {
+    action: fallbackAction,
+    triggerSource: fallbackTrigger,
+    score,
+    relayDecodedDomain,
+    features: {
+      ...scoreResult,
+      domainBlocked: false,
+      relayDecoded: !!relayDecodedDomain,
+      brandMatch,
+      randomTokens,
+    },
+  };
+}
diff --git a/backend/tests/mail/mail-classifier.test.ts b/backend/tests/mail/mail-classifier.test.ts
new file mode 100644
index 0000000..ae8ad2c
--- /dev/null
+++ b/backend/tests/mail/mail-classifier.test.ts
@@ -0,0 +1,517 @@
+/**
+ * Tests für mail-classifier.ts — Mail-Klassifikations-Pipeline.
+ *
+ * Testet alle Layer-Logiken als pure Funktionen (kein DB-Mock, kein Groq-Mock).
+ *
+ * Abgedeckt:
+ *   - extractRelayedDomain() — diverse Relay-Patterns
+ *   - normalizeBrand() — Normalisierungs-Logik
+ *   - hasRandomTokens() — true/false cases
+ *   - redactLocalPartForLLM() — keep vs redact
+ *   - computeScore() — Score-Berechnung mit Weights
+ *   - classifyMail() — End-to-End Pipeline:
+ *       - Gamblezen-Beispiel → Layer 2.5 Hard-Block (kein LLM-Call)
+ *       - BetandPlay-Beispiel → Layer 2.5 Hard-Block (kein LLM-Call)
+ *       - Whitelist-Case (wettervorhersage)
+ *       - Domain-Block (Layer 2)
+ *       - Relay-Decoded Block (Layer 2)
+ *       - No-Signal → PASS
+ */
+import { describe, it, expect, vi } from "vitest";
+
+// gambling-keywords.mjs ist ESM ohne TypeScript — mock before import
+vi.mock("../../server/utils/gambling-keywords.mjs", () => ({
+  GAMBLING_KEYWORDS: [
+    "casino", "bet365", "bwin", "tipico", "unibet", "betway",
+    "pokerstars", "jackpot", "freispiel", "free spin", "bonus code",
+    "auszahlung", "glücksspiel", "slots", "roulette", "wette",
+    "stake", "rolletto", "vbet", "1xbet", "melbet", "mostbet",
+    "luckyvibe", "spinz", "casinoly", "rabona", "justcasino",
+    "getslots", "rocketplay", "freshcasino", "betano", "leovegas",
+  ],
+  GAMBLING_WHITELIST: [
+    "wettervorhersage",
+    "wetter",
+    "wetterbericht",
+    "wettkampf",
+    "wettbewerb",
+  ],
+}));
+
+import {
+  extractRelayedDomain,
+  normalizeBrand,
+  hasRandomTokens,
+  redactLocalPartForLLM,
+  computeScore,
+  classifyMail,
+  matchesGamblingBrand,
+} from "../../server/utils/mail-classifier";
+
+// ─── extractRelayedDomain ────────────────────────────────────────────────────
+
+describe("extractRelayedDomain()", () => {
+  it("extrahiert Domain aus SendGrid-bounce-Pattern (user=domain@sendgrid)", () => {
+    expect(extractRelayedDomain("bounces+user=gamblezen.com@sendgrid.net"))
+      .toBe("gamblezen.com");
+  });
+
+  it("extrahiert Domain aus Mailchimp-Track-Pattern (track.user=domain@mc)", () => {
+    expect(extractRelayedDomain("track.user=betandplay.com@mailchimp.com"))
+      .toBe("betandplay.com");
+  });
+
+  it("extrahiert Domain aus _at_-Pattern", () => {
+    expect(extractRelayedDomain("a1b2c3_user_at_betandplay.com@em.example.com"))
+      .toBe("betandplay.com");
+  });
+
+  it("gibt null zurück wenn kein Relay-Pattern erkannt", () => {
+    expect(extractRelayedDomain("info@betandplay.com")).toBeNull();
+  });
+
+  it("gibt null zurück für direkte Adressen ohne @", () => {
+    expect(extractRelayedDomain("noatsign")).toBeNull();
+  });
+
+  it("normalisiert extrahierte Domain auf lowercase", () => {
+    expect(extractRelayedDomain("bounce=GambleZen.COM@delivery.net"))
+      .toBe("gamblezen.com");
+  });
+
+  it("gibt null zurück für normale Adressen ohne Relay-Muster", () => {
+    expect(extractRelayedDomain("newsletter@example.org")).toBeNull();
+  });
+});
+
+// ─── normalizeBrand ──────────────────────────────────────────────────────────
+
+describe("normalizeBrand()", () => {
+  it("BetandPlay → betandplay", () => {
+    expect(normalizeBrand("BetandPlay")).toBe("betandplay");
+  });
+
+  it("bet-and-play → betandplay", () => {
+    expect(normalizeBrand("bet-and-play")).toBe("betandplay");
+  });
+
+  it("Gamble Zen → gamblezen", () => {
+    expect(normalizeBrand("Gamble Zen")).toBe("gamblezen");
+  });
+
+  it("Mr. Green → mrgreen", () => {
+    expect(normalizeBrand("Mr. Green")).toBe("mrgreen");
+  });
+
+  it("lucky_vibe → luckyvibe", () => {
+    expect(normalizeBrand("lucky_vibe")).toBe("luckyvibe");
+  });
+
+  it("unveränderte Kleinbuchstaben bleiben gleich", () => {
+    expect(normalizeBrand("casino")).toBe("casino");
+  });
+});
+
+// ─── matchesGamblingBrand ────────────────────────────────────────────────────
+
+describe("matchesGamblingBrand()", () => {
+  it("'gamblezen' matcht", () => {
+    expect(matchesGamblingBrand("gamblezen")).toBe(true);
+  });
+
+  it("'betandplay' matcht", () => {
+    expect(matchesGamblingBrand("betandplay")).toBe(true);
+  });
+
+  it("'casino' matcht (exact)", () => {
+    expect(matchesGamblingBrand("casino")).toBe(true);
+  });
+
+  it("'mrgreen' matcht", () => {
+    expect(matchesGamblingBrand("mrgreen")).toBe(true);
+  });
+
+  it("'example' matcht nicht", () => {
+    expect(matchesGamblingBrand("example")).toBe(false);
+  });
+
+  it("zu kurze Strings (< 4 Zeichen) matchen nie", () => {
+    expect(matchesGamblingBrand("bet")).toBe(false);
+  });
+
+  it("'googlemail' matcht nicht", () => {
+    expect(matchesGamblingBrand("googlemail")).toBe(false);
+  });
+});
+
+// ─── hasRandomTokens ─────────────────────────────────────────────────────────
+
+describe("hasRandomTokens()", () => {
+  it("local-part mit 2+ zufälligen Tokens → true", () => {
+    // Gamblezen-typisch: hq3a91_7xmpl2 (2 random-looking tokens)
+    expect(hasRandomTokens("hq3a91_7xmpl2")).toBe(true);
+  });
+
+  it("local-part mit User-ID + Token → true", () => {
+    expect(hasRandomTokens("user123abc_ref456xyz")).toBe(true);
+  });
+
+  it("'info' → false (Funktionswort)", () => {
+    expect(hasRandomTokens("info")).toBe(false);
+  });
+
+  it("'noreply' → false (Funktionswort)", () => {
+    expect(hasRandomTokens("noreply")).toBe(false);
+  });
+
+  it("'newsletter' → false (Funktionswort, kein Digit-Mix)", () => {
+    expect(hasRandomTokens("newsletter")).toBe(false);
+  });
+
+  it("normaler Local-Part ohne Zufalls-Tokens → false", () => {
+    expect(hasRandomTokens("john.doe")).toBe(false);
+  });
+
+  it("nur ein random Token (Grenzfall) → false", () => {
+    // Nur ein Token >= 6 mit Digit-Mix → unter Schwelle (braucht >= 2)
+    expect(hasRandomTokens("abc123")).toBe(false);
+  });
+
+  it("echter BetandPlay-typischer Local-Part → true", () => {
+    // z.B. "u7a2b1_offers_ref9x2z" — ein Funktionswort + 2 random tokens
+    expect(hasRandomTokens("u7a2b1_offers_ref9x2z")).toBe(true);
+  });
+});
+
+// ─── redactLocalPartForLLM ───────────────────────────────────────────────────
+
+describe("redactLocalPartForLLM()", () => {
+  it("normale Adresse → local-part wird redacted", () => {
+    expect(redactLocalPartForLLM("user123@example.com", false))
+      .toBe("***@example.com");
+  });
+
+  it("Adresse mit Casino-Keyword im local-part → NICHT redacted", () => {
+    expect(redactLocalPartForLLM("casino_offers@mailer.net", true))
+      .toBe("casino_offers@mailer.net");
+  });
+
+  it("normal ohne Keyword-Flag → redacted", () => {
+    expect(redactLocalPartForLLM("a1b2c3_track@sendgrid.net", false))
+      .toBe("***@sendgrid.net");
+  });
+
+  it("Adresse ohne @ → unverändert zurückgegeben", () => {
+    expect(redactLocalPartForLLM("noatsign", false)).toBe("noatsign");
+  });
+});
+
+// ─── computeScore ────────────────────────────────────────────────────────────
+
+describe("computeScore()", () => {
+  it("Whitelist-Hit → score=0, whitelistHit=true", () => {
+    const result = computeScore(
+      "info@wetter.de",
+      "Wetter Service",
+      "Wettervorhersage für morgen",
+      false,
+      false,
+    );
+    expect(result.whitelistHit).toBe(true);
+    expect(result.score).toBe(0);
+  });
+
+  it("Casino im Betreff → SUBJECT_GAMBLING_KEYWORD += 35", () => {
+    const result = computeScore(
+      "info@example.com",
+      null,
+      "Dein Casino-Bonus wartet",
+      false,
+      false,
+    );
+    expect(result.keywordHitsSubject).toContain("casino");
+    expect(result.score).toBeGreaterThanOrEqual(35);
+  });
+
+  it("Geld-Pattern (100€) im Betreff → SUBJECT_MONEY_PATTERN += 20", () => {
+    const result = computeScore(
+      "info@example.com",
+      null,
+      "100€ Willkommensbonus jetzt sichern",
+      false,
+      false,
+    );
+    expect(result.styleFlags).toContain("money-pattern");
+    expect(result.score).toBeGreaterThanOrEqual(20);
+  });
+
+  it("Brand-Match ohne Random → BRAND_MATCH_NO_RANDOM += 35", () => {
+    const result = computeScore(
+      "info@example.com",
+      null,
+      "Normaler Betreff",
+      true,  // brandMatch=true
+      false, // randomTokens=false
+    );
+    expect(result.score).toBeGreaterThanOrEqual(35);
+  });
+
+  it("Random-Tokens ohne Brand → RANDOM_TOKENS_NO_BRAND += 10", () => {
+    const result = computeScore(
+      "info@example.com",
+      null,
+      "Newsletter vom Tag",
+      false, // brandMatch=false
+      true,  // randomTokens=true
+    );
+    expect(result.score).toBeGreaterThanOrEqual(10);
+  });
+
+  it("Score wird auf max 100 gecapped", () => {
+    // Alle Signale gleichzeitig → Score würde > 100 sein
+    const result = computeScore(
+      "slots@casinobonus.bet",
+      "Casino Jackpot",
+      "JACKPOT Casino 500€ Freispiele Nur heute Letzte chance",
+      true,
+      true,
+    );
+    expect(result.score).toBeLessThanOrEqual(100);
+  });
+});
+
+// ─── classifyMail() — Pipeline End-to-End ────────────────────────────────────
+
+describe("classifyMail() — End-to-End Pipeline", () => {
+  // Leere Domain-Set für die meisten Tests (kein Domain-Hard-Block)
+  const emptyDomainSet = new Set<string>();
+
+  // ─── Screenshot-Beispiel 1: Gamblezen via Relay ───────────────────────────
+  it("Gamblezen-Beispiel: bounces+user=gamblezen.com@em.sendgrid.net → Layer 2.5 Hard-Block", async () => {
+    // Gamblezen leitet über SendGrid-Bounces: Domain "em.sendgrid.net" ist nicht geblockt,
+    // aber relay-decoded → "gamblezen.com" + local-part hat random tokens.
+    // gamblezen.com ist ein bekannter Gambling-Brand.
+    const domainSetWithGamblezen = new Set(["gamblezen.com"]);
+
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "bounces+user=gamblezen.com@em.sendgrid.net",
+        senderName: "Gamble Zen",
+        subject: "Dein exklusives Angebot wartet",
+      },
+      blockedDomainSet: domainSetWithGamblezen,
+      groqApiKey: "", // kein LLM erlaubt hier
+    });
+
+    // Relay-decoded domain matcht blocklist → Layer 2 (relay-decoded), NICHT Layer 2.5
+    expect(result.action).toBe("blocked");
+    expect(result.triggerSource).toBe("relay-decoded");
+    expect(result.relayDecodedDomain).toBe("gamblezen.com");
+  });
+
+  it("Gamblezen-Beispiel ohne Blocklist-Entry → Layer 2.5 Hard-Block via Brand+Random", async () => {
+    // Wenn gamblezen.com NICHT in der Blocklist ist: Brand+Random greift trotzdem
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "hq3a91_7xmpl2@em.sendgrid.net",
+        senderName: "Gamble Zen", // Brand-Match via Display-Name
+        subject: "Dein exklusives Angebot wartet",
+      },
+      blockedDomainSet: emptyDomainSet,
+      groqApiKey: "", // kein LLM-Call hier erwartet
+    });
+
+    expect(result.action).toBe("blocked");
+    expect(result.triggerSource).toBe("brand+random");
+    expect(result.features.brandMatch).toBe(true);
+    expect(result.features.randomTokens).toBe(true);
+  });
+
+  // ─── Screenshot-Beispiel 2: BetandPlay via Relay ─────────────────────────
+  it("BetandPlay-Beispiel: track.user=betandplay.com@mailchimp.com → Layer 2.5 Hard-Block", async () => {
+    const domainSetWithBetandPlay = new Set(["betandplay.com"]);
+
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "track.user=betandplay.com@mailchimp.com",
+        senderName: "BetandPlay",
+        subject: "100€ Willkommensbonus — Nur heute!",
+      },
+      blockedDomainSet: domainSetWithBetandPlay,
+      groqApiKey: "",
+    });
+
+    expect(result.action).toBe("blocked");
+    expect(result.triggerSource).toBe("relay-decoded");
+    expect(result.relayDecodedDomain).toBe("betandplay.com");
+  });
+
+  it("BetandPlay-Beispiel ohne Blocklist-Entry → Layer 2.5 Hard-Block via Brand+Random", async () => {
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "u7a2b1_offers_ref9x2z@mailchimp.com",
+        senderName: "BetandPlay", // Brand-Match via Display-Name
+        subject: "100€ Willkommensbonus",
+      },
+      blockedDomainSet: emptyDomainSet,
+      groqApiKey: "",
+    });
+
+    expect(result.action).toBe("blocked");
+    expect(result.triggerSource).toBe("brand+random");
+    expect(result.features.brandMatch).toBe(true);
+    expect(result.features.randomTokens).toBe(true);
+  });
+
+  // ─── Layer 1: Whitelist ───────────────────────────────────────────────────
+  it("Whitelist-Treffer: 'wettervorhersage' im Betreff → PASS", async () => {
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "service@wetter.de",
+        senderName: "Wetter.de",
+        subject: "Wettervorhersage für morgen",
+      },
+      blockedDomainSet: emptyDomainSet,
+      groqApiKey: "",
+    });
+
+    expect(result.action).toBe("passed");
+    expect(result.triggerSource).toBe("whitelist");
+  });
+
+  it("'wettkampf' in Betreff → PASS (kein Gambling trotz 'wette')", async () => {
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "info@sport.de",
+        senderName: null,
+        subject: "Wettkampf-Ergebnisse dieser Woche",
+      },
+      blockedDomainSet: emptyDomainSet,
+      groqApiKey: "",
+    });
+
+    expect(result.action).toBe("passed");
+    expect(result.triggerSource).toBe("whitelist");
+  });
+
+  // ─── Layer 2: Domain-Hard-Block ───────────────────────────────────────────
+  it("Domain in Blocklist → Layer 2 Hard-Block", async () => {
+    const domainSet = new Set(["casinoly.com"]);
+
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "promo@casinoly.com",
+        senderName: "Casinoly",
+        subject: "Dein Bonus wartet",
+      },
+      blockedDomainSet: domainSet,
+      groqApiKey: "",
+    });
+
+    expect(result.action).toBe("blocked");
+    expect(result.triggerSource).toBe("domain");
+    expect(result.features.domainBlocked).toBe(true);
+  });
+
+  // ─── Relay-Decoded Block ──────────────────────────────────────────────────
+  it("Relay-Decoded: =domain.com in local-part und Domain in Blocklist → relay-decoded Block", async () => {
+    const domainSet = new Set(["rabona.com"]);
+
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "bounce+track=rabona.com@em.sendgrid.net",
+        senderName: "Rabona Casino",
+        subject: "Exklusiv für dich",
+      },
+      blockedDomainSet: domainSet,
+      groqApiKey: "",
+    });
+
+    expect(result.action).toBe("blocked");
+    expect(result.triggerSource).toBe("relay-decoded");
+    expect(result.relayDecodedDomain).toBe("rabona.com");
+  });
+
+  // ─── Layer 3: Score-Block (ohne LLM) ──────────────────────────────────────
+  it("Viele Signale → Score >= 80 → Hard-Block ohne LLM", async () => {
+    // Casino im Sender-Name + Jackpot im Betreff + Urgency + Geld-Pattern
+    const groqCallSpy = vi.fn();
+
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "info@spinz-casino.example",
+        senderName: "Casino Jackpot Club",
+        subject: "JACKPOT 500€ Freispiele — Nur heute!",
+      },
+      blockedDomainSet: emptyDomainSet,
+      groqApiKey: "should-not-be-called",
+    });
+
+    expect(result.action).toBe("blocked");
+    expect(result.triggerSource).toMatch(/^score:/);
+    expect(result.score).toBeGreaterThanOrEqual(80);
+    // groqCallSpy wurde nicht gecallt weil wir fetch nicht mocken —
+    // aber score >= 80 bedeutet Layer 4 wird gar nicht erreicht
+  });
+
+  // ─── No-Signal → PASS ────────────────────────────────────────────────────
+  it("unauffällige Mail → PASS mit triggerSource 'no-signal'", async () => {
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "newsletter@amazon.de",
+        senderName: "Amazon",
+        subject: "Deine Bestellung wurde versandt",
+      },
+      blockedDomainSet: emptyDomainSet,
+      groqApiKey: "",
+    });
+
+    expect(result.action).toBe("passed");
+    expect(result.triggerSource).toBe("no-signal");
+    expect(result.score).toBeLessThan(25);
+  });
+
+  // ─── Brand-Match ohne Random → kein Hard-Block, Score-Erhöhung ───────────
+  it("Brand-Match ohne Random-Tokens → kein Layer-2.5-Block, aber Score-Erhöhung", async () => {
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "info@betandplay.com", // direktes info@, kein random
+        senderName: "BetandPlay",
+        subject: "Willkommen",
+      },
+      blockedDomainSet: emptyDomainSet,
+      groqApiKey: "",
+    });
+
+    // Kein Hard-Block Layer 2.5 (kein Random), aber Score erhöht durch Brand-Match
+    expect(result.triggerSource).not.toBe("brand+random");
+    expect(result.features.brandMatch).toBe(true);
+    expect(result.features.randomTokens).toBe(false);
+    // Score >= 35 (BRAND_MATCH_NO_RANDOM) — endet je nach anderen Signalen
+    expect(result.features.score).toBeGreaterThanOrEqual(35);
+  });
+
+  // ─── Korrekte Feature-Struktur im Result ─────────────────────────────────
+  it("Result-Features enthalten alle erwarteten Keys", async () => {
+    const result = await classifyMail({
+      mail: {
+        senderEmail: "promo@example.com",
+        senderName: null,
+        subject: "Test",
+      },
+      blockedDomainSet: emptyDomainSet,
+      groqApiKey: "",
+    });
+
+    expect(result.features).toHaveProperty("score");
+    expect(result.features).toHaveProperty("domainBlocked");
+    expect(result.features).toHaveProperty("relayDecoded");
+    expect(result.features).toHaveProperty("brandMatch");
+    expect(result.features).toHaveProperty("randomTokens");
+    expect(result.features).toHaveProperty("keywordHitsSubject");
+    expect(result.features).toHaveProperty("keywordHitsDomain");
+    expect(result.features).toHaveProperty("keywordHitsName");
+    expect(result.features).toHaveProperty("styleFlags");
+    expect(result.features).toHaveProperty("whitelistHit");
+  });
+});