diff --git a/src/app/api/campaigns/[id]/send/route.ts b/src/app/api/campaigns/[id]/send/route.ts
index 5aac37f..d4a9c81 100644
--- a/src/app/api/campaigns/[id]/send/route.ts
+++ b/src/app/api/campaigns/[id]/send/route.ts
@@ -1,7 +1,6 @@
 import { NextRequest, NextResponse } from 'next/server'
-import { getCampaign, updateCampaignStatus } from '../../../../../server/db/campaigns'
+import { getCampaign, updateCampaignStatus, getCampaignRecipients } from '../../../../../server/db/campaigns'
 import { emailSendQueue } from '../../../../../queues/email-send.queue'
-import { withTenant } from '../../../../../server/db/tenant'
 import { hashEmail } from '../../../../../lib/crypto'
 import { checkSuppression } from '../../../../../server/suppression/check'
 import { getTenantId } from '../../../../../lib/tenant-header'
@@ -25,22 +24,13 @@ export async function POST(req: NextRequest, { params }: { params: { id: string
     return NextResponse.json({ error: statusResult.error.message }, { status: 500 })
   }
 
-  let recipients: { email: string }[]
-  try {
-    recipients = await withTenant(tenantId, (client) =>
-      client.query<{ email: string }>(
-        `SELECT s.email FROM subscribers s
-         JOIN campaign_recipients cr ON cr.campaign_id = $1
-         WHERE (cr.list_id IS NULL OR s.list_id = cr.list_id)
-           AND s.status = 'active'`,
-        [params.id]
-      )
-    )
-  } catch (e) {
+  const recipientsResult = await getCampaignRecipients(tenantId, params.id)
+  if (!recipientsResult.ok) {
     // Rollback auf draft — verhindert verwaisten 'sending'-Status
     await updateCampaignStatus(tenantId, params.id, 'draft')
     return NextResponse.json({ error: 'Empfänger konnten nicht geladen werden' }, { status: 500 })
   }
+  const recipients = recipientsResult.data
 
   // Suppression-Check PFLICHT — kein Opt-out-Empfänger darf in die Queue
   const unsuppressedRecipients = await Promise.all(
diff --git a/src/app/api/campaigns/campaigns-api.test.ts b/src/app/api/campaigns/campaigns-api.test.ts
index b6c18ee..cb951e8 100644
--- a/src/app/api/campaigns/campaigns-api.test.ts
+++ b/src/app/api/campaigns/campaigns-api.test.ts
@@ -1,9 +1,26 @@
-import { describe, it, expect } from 'vitest'
+import { describe, it, expect, vi } from 'vitest'
 
-// Dieser Test-Block ist übersprungen, weil next/server in Vitest nicht
-// vollständig verfügbar ist. Die Haupttests sind die bestehenden Unit-Tests
-// in src/queues/, src/server/ und src/lib/.
-describe.skip('API Route Exports', () => {
+vi.mock('../../../server/db/campaigns', () => ({
+  createCampaign: vi.fn(),
+  listCampaigns: vi.fn(),
+  getCampaign: vi.fn(),
+  updateCampaign: vi.fn(),
+  updateCampaignStatus: vi.fn(),
+  getCampaignRecipients: vi.fn(),
+}))
+vi.mock('../../../queues/email-send.queue', () => ({
+  emailSendQueue: { addBulk: vi.fn() },
+}))
+vi.mock('../../../server/suppression/check', () => ({
+  checkSuppression: vi.fn(),
+}))
+vi.mock('../../../lib/validation', () => ({
+  CreateCampaignSchema: { safeParse: vi.fn().mockReturnValue({ success: false, error: { issues: [] } }) },
+  UpdateCampaignSchema: { safeParse: vi.fn().mockReturnValue({ success: false, error: { issues: [] } }) },
+  ScheduleCampaignSchema: { safeParse: vi.fn().mockReturnValue({ success: false, error: { issues: [] } }) },
+}))
+
+describe('API Route Exports', () => {
   it('route.ts exportiert GET und POST', async () => {
     const mod = await import('./route')
     expect(typeof mod.GET).toBe('function')
diff --git a/src/server/db/campaigns.test.ts b/src/server/db/campaigns.test.ts
index f25d59e..69ddcac 100644
--- a/src/server/db/campaigns.test.ts
+++ b/src/server/db/campaigns.test.ts
@@ -15,6 +15,7 @@ import {
   updateCampaign,
   listCampaigns,
   updateCampaignStatus,
+  getCampaignRecipients,
 } from './campaigns'
 
 const mockRow = {
@@ -31,7 +32,7 @@ const mockRow = {
 }
 
 describe('createCampaign', () => {
-  beforeEach(() => vi.clearAllMocks())
+  beforeEach(() => mockClient.query.mockReset())
 
   it('gibt erstellte Kampagne zurück', async () => {
     mockClient.query.mockResolvedValueOnce([mockRow])
@@ -55,7 +56,7 @@ describe('createCampaign', () => {
 })
 
 describe('getCampaign', () => {
-  beforeEach(() => vi.clearAllMocks())
+  beforeEach(() => mockClient.query.mockReset())
 
   it('gibt Kampagne zurück wenn gefunden', async () => {
     mockClient.query.mockResolvedValueOnce([mockRow])
@@ -72,7 +73,7 @@ describe('getCampaign', () => {
 })
 
 describe('listCampaigns', () => {
-  beforeEach(() => vi.clearAllMocks())
+  beforeEach(() => mockClient.query.mockReset())
 
   it('gibt leeres Array zurück wenn keine Kampagnen', async () => {
     mockClient.query.mockResolvedValueOnce([])
@@ -89,10 +90,12 @@ describe('listCampaigns', () => {
 })
 
 describe('updateCampaign', () => {
-  beforeEach(() => vi.clearAllMocks())
+  beforeEach(() => mockClient.query.mockReset())
 
   it('aktualisiert nur übergebene Felder', async () => {
-    mockClient.query.mockResolvedValueOnce([{ ...mockRow, name: 'Neu' }])
+    mockClient.query
+      .mockResolvedValueOnce([{ id: 'uuid-1', status: 'draft' }])  // SELECT Existenz-Check
+      .mockResolvedValueOnce([{ ...mockRow, name: 'Neu' }])          // UPDATE RETURNING
     const result = await updateCampaign('tenant1', 'uuid-1', { name: 'Neu' })
     expect(result.ok).toBe(true)
     if (result.ok) expect(result.data.name).toBe('Neu')
@@ -103,16 +106,54 @@ describe('updateCampaign', () => {
     expect(result.ok).toBe(false)
   })
 
-  it('gibt err zurück wenn Kampagne nicht im Draft-Status', async () => {
-    mockClient.query.mockResolvedValueOnce([])
+  it('gibt err mit "nicht gefunden" zurück wenn Kampagne nicht existiert', async () => {
+    // Bug 2: muss "nicht gefunden" melden, nicht "Draft-Status"
+    mockClient.query.mockResolvedValueOnce([])  // SELECT: nicht gefunden
+    const result = await updateCampaign('tenant1', 'uuid-nicht-existent', { name: 'Neu' })
+    expect(result.ok).toBe(false)
+    if (!result.ok) expect(result.error.message).toContain('nicht gefunden')
+  })
+
+  it('gibt err mit "Draft-Status" zurück wenn Kampagne nicht im Draft ist', async () => {
+    mockClient.query.mockResolvedValueOnce([{ id: 'uuid-1', status: 'sent' }])  // SELECT: gefunden, aber sent
     const result = await updateCampaign('tenant1', 'uuid-1', { name: 'Neu' })
     expect(result.ok).toBe(false)
     if (!result.ok) expect(result.error.message).toContain('Draft-Status')
   })
 })
 
+describe('getCampaignRecipients', () => {
+  beforeEach(() => mockClient.query.mockReset())
+
+  it('nutzt EXISTS-Subquery statt Cross-Join', async () => {
+    mockClient.query.mockResolvedValueOnce([{ email: 'a@example.com' }])
+    await getCampaignRecipients('tenant1', 'campaign-1')
+    const [sql] = mockClient.query.mock.calls[0] as [string, unknown[]]
+    // Bug 1: muss EXISTS statt JOIN verwenden um Duplikate zu vermeiden
+    expect(sql).toContain('EXISTS')
+    expect(sql).not.toMatch(/JOIN.*campaign_recipients.*ON.*campaign_id\s*=\s*\$1/i)
+  })
+
+  it('gibt deduplizierte E-Mail-Adressen zurück', async () => {
+    mockClient.query.mockResolvedValueOnce([
+      { email: 'a@example.com' },
+      { email: 'b@example.com' },
+    ])
+    const result = await getCampaignRecipients('tenant1', 'campaign-1')
+    expect(result.ok).toBe(true)
+    if (result.ok) expect(result.data).toHaveLength(2)
+  })
+
+  it('gibt leeres Array zurück wenn keine Empfänger', async () => {
+    mockClient.query.mockResolvedValueOnce([])
+    const result = await getCampaignRecipients('tenant1', 'campaign-1')
+    expect(result.ok).toBe(true)
+    if (result.ok) expect(result.data).toEqual([])
+  })
+})
+
 describe('updateCampaignStatus', () => {
-  beforeEach(() => vi.clearAllMocks())
+  beforeEach(() => mockClient.query.mockReset())
 
   it('setzt Status auf scheduled', async () => {
     mockClient.query.mockResolvedValueOnce([{ ...mockRow, status: 'scheduled' }])
diff --git a/src/server/db/campaigns.ts b/src/server/db/campaigns.ts
index 1dd5e10..582e633 100644
--- a/src/server/db/campaigns.ts
+++ b/src/server/db/campaigns.ts
@@ -79,15 +79,48 @@ export async function updateCampaign(
   if (fields.length === 0) return err(new Error('Keine Felder zum Aktualisieren'))
 
   try {
-    values.push(id)
-    const rows = await withTenant(tenantId, (client) =>
-      client.query(
-        `UPDATE campaigns SET ${fields.join(', ')} WHERE id = $${idx} AND status = 'draft' RETURNING *`,
+    return await withTenant(tenantId, async (client) => {
+      // Bug 2: Existenz und Status getrennt prüfen um korrekten Fehler zu melden
+      const existing = await client.query<{ id: string; status: string }>(
+        'SELECT id, status FROM campaigns WHERE id = $1',
+        [id]
+      )
+      if (existing.length === 0) return err(new Error('Kampagne nicht gefunden'))
+      if (existing[0].status !== 'draft') return err(new Error('Kampagne nicht im Draft-Status'))
+
+      values.push(id)
+      const rows = await client.query(
+        `UPDATE campaigns SET ${fields.join(', ')} WHERE id = $${idx} RETURNING *`,
         values
       )
+      if (rows.length === 0) return err(new Error('Kampagne nicht gefunden'))
+      return ok(rowToCampaign(rows[0]))
+    })
+  } catch (e) {
+    return err(e instanceof Error ? e : new Error(String(e)))
+  }
+}
+
+export async function getCampaignRecipients(
+  tenantId: string,
+  campaignId: string
+): Promise<Result<{ email: string }[]>> {
+  try {
+    // Bug 1: EXISTS-Subquery verhindert Duplikate durch kartesisches Produkt
+    const rows = await withTenant(tenantId, (client) =>
+      client.query<{ email: string }>(
+        `SELECT s.email
+         FROM subscribers s
+         WHERE s.status = 'active'
+           AND EXISTS (
+             SELECT 1 FROM campaign_recipients cr
+             WHERE cr.campaign_id = $1
+               AND (cr.list_id IS NULL OR cr.list_id = s.list_id)
+           )`,
+        [campaignId]
+      )
     )
-    if (rows.length === 0) return err(new Error('Kampagne nicht im Draft-Status'))
-    return ok(rowToCampaign(rows[0]))
+    return ok(rows)
   } catch (e) {
     return err(e instanceof Error ? e : new Error(String(e)))
   }