feat(mailer): gate outbound email on AppConfig access-control ban list (#5018)

* Revert "improvement(auth): layer disposable-email-domains into signup email validation (#5010)"

This reverts commit 2c0a10a.

* feat(mailer): gate outbound email on AppConfig access-control ban list

* ci(migrations): restore dev schema-push TTY rename/drop guard dropped by #5010 revert

Author: TheodoreSpeaks

apps/sim/lib/messaging/email/mailer.test.ts

@@ -36,6 +36,17 @@ vi.mock('@/lib/messaging/email/unsubscribe', () => ({
   generateUnsubscribeToken: vi.fn(),
 }))
 
+vi.mock('@/lib/auth/access-control', () => ({
+  getAccessControlConfig: vi.fn().mockResolvedValue({
+    blockedSignupDomains: [],
+    blockedEmails: [],
+    allowedLoginEmails: [],
+    allowedLoginDomains: [],
+    blockedEmailMxHosts: [],
+  }),
+  isEmailBlockedByAccessControl: vi.fn().mockReturnValue(false),
+}))
+
 vi.mock('@/lib/core/config/env', () =>
   createEnvMock({
     RESEND_API_KEY: 'test-api-key',
@@ -59,6 +70,7 @@ vi.mock('@/lib/messaging/email/utils', () => ({
   NO_EMAIL_HEADER_CONTROL_CHARS_REGEX: /^[^\r\n]*$/,
 }))
 
+import { isEmailBlockedByAccessControl } from '@/lib/auth/access-control'
 import { type EmailType, hasEmailService, sendBatchEmails, sendEmail } from './mailer'
 import { generateUnsubscribeToken, isUnsubscribed } from './unsubscribe'
 
@@ -71,6 +83,7 @@ describe('mailer', () => {
 
   beforeEach(() => {
     vi.clearAllMocks()
+    ;(isEmailBlockedByAccessControl as Mock).mockReturnValue(false)
     ;(isUnsubscribed as Mock).mockResolvedValue(false)
     ;(generateUnsubscribeToken as Mock).mockReturnValue('mock-token-123')
 
@@ -195,6 +208,36 @@ describe('mailer', () => {
       expect(isUnsubscribed).toHaveBeenCalledWith('user1@example.com', 'marketing')
     })
 
+    it('should skip sending when the recipient is on the ban list', async () => {
+      ;(isEmailBlockedByAccessControl as Mock).mockReturnValue(true)
+
+      const result = await sendEmail({
+        ...testEmailOptions,
+        emailType: 'transactional',
+      })
+
+      expect(result.success).toBe(true)
+      expect(result.message).toBe('Email skipped (recipient on access-control ban list)')
+      expect(result.data).toEqual({ id: 'skipped-banned' })
+      expect(mockSend).not.toHaveBeenCalled()
+      expect(isUnsubscribed).not.toHaveBeenCalled()
+    })
+
+    it('should drop only the banned recipients from a multi-recipient send', async () => {
+      ;(isEmailBlockedByAccessControl as Mock).mockImplementation(
+        (email: string) => email === 'banned@example.com'
+      )
+
+      const result = await sendEmail({
+        ...testEmailOptions,
+        to: ['good@example.com', 'banned@example.com'],
+        emailType: 'transactional',
+      })
+
+      expect(result.success).toBe(true)
+      expect(mockSend).toHaveBeenCalledWith(expect.objectContaining({ to: 'good@example.com' }))
+    })
+
     it('should handle general exceptions gracefully', async () => {
       ;(isUnsubscribed as Mock).mockRejectedValue(new Error('Database connection failed'))
 
@@ -256,6 +299,20 @@ describe('mailer', () => {
       expect(isUnsubscribed).not.toHaveBeenCalled()
     })
 
+    it('should skip banned recipients in a batch', async () => {
+      ;(isEmailBlockedByAccessControl as Mock).mockImplementation(
+        (email: string) => email === 'user2@example.com'
+      )
+
+      const result = await sendBatchEmails({ emails: testBatchEmails })
+
+      expect(result.results).toHaveLength(2)
+      const bannedEntry = result.results.find(
+        (r) => r.message === 'Email skipped (recipient on access-control ban list)'
+      )
+      expect(bannedEntry).toBeDefined()
+    })
+
     it('should degrade isUnsubscribed rejections to per-entry failures', async () => {
       ;(isUnsubscribed as Mock).mockRejectedValue(new Error('Database connection failed'))
 

apps/sim/lib/messaging/email/mailer.ts

@@ -1,5 +1,6 @@
 import { createLogger } from '@sim/logger'
 import { getErrorMessage } from '@sim/utils/errors'
+import { getAccessControlConfig, isEmailBlockedByAccessControl } from '@/lib/auth/access-control'
 import { processEmailData, shouldSkipForUnsubscribe } from '@/lib/messaging/email/prepare'
 import { activeProviders } from '@/lib/messaging/email/providers'
 import type {
@@ -36,22 +37,54 @@ const MOCK_EMAIL_RESULT: SendEmailResult = {
   data: { id: 'mock-email-id' },
 }
 
+const SKIPPED_BANNED_RESULT: SendEmailResult = {
+  success: true,
+  message: 'Email skipped (recipient on access-control ban list)',
+  data: { id: 'skipped-banned' },
+}
+
 export function hasEmailService(): boolean {
   return activeProviders.length > 0
 }
 
+/**
+ * Drop recipients that are on the AppConfig access-control ban list. Returns the
+ * original options when nothing is banned, options narrowed to the allowed
+ * recipients when some are, or `null` when every recipient is banned. Config is
+ * cached (~30s TTL) with an env fallback, so a missing/unreachable AppConfig
+ * fails open rather than blocking all mail.
+ */
+async function applyBanList(options: EmailOptions): Promise<EmailOptions | null> {
+  const recipients = Array.isArray(options.to) ? options.to : [options.to]
+  const config = await getAccessControlConfig()
+  const allowed = recipients.filter((email) => !isEmailBlockedByAccessControl(email, config))
+  if (allowed.length === 0) return null
+  if (allowed.length === recipients.length) return options
+  return { ...options, to: allowed.length === 1 ? allowed[0] : allowed }
+}
+
 export async function sendEmail(options: EmailOptions): Promise<SendEmailResult> {
   try {
-    if (await shouldSkipForUnsubscribe(options)) {
-      logger.info('Email not sent (user unsubscribed):', {
+    const allowed = await applyBanList(options)
+    if (!allowed) {
+      logger.info('Email not sent (recipient on access-control ban list):', {
         to: options.to,
         subject: options.subject,
         emailType: options.emailType,
       })
+      return SKIPPED_BANNED_RESULT
+    }
+
+    if (await shouldSkipForUnsubscribe(allowed)) {
+      logger.info('Email not sent (user unsubscribed):', {
+        to: allowed.to,
+        subject: allowed.subject,
+        emailType: allowed.emailType,
+      })
       return SKIPPED_UNSUBSCRIBED_RESULT
     }
 
-    const data = processEmailData(options)
+    const data = processEmailData(allowed)
 
     if (activeProviders.length === 0) {
       logger.info('Email not sent (no email service configured):', {
@@ -96,10 +129,14 @@ async function prepareBatch(emails: EmailOptions[]): Promise<PreparedBatchEntry[
   return Promise.all(
     emails.map(async (email, index): Promise<PreparedBatchEntry> => {
       try {
-        if (await shouldSkipForUnsubscribe(email)) {
+        const allowed = await applyBanList(email)
+        if (!allowed) {
+          return { index, data: null, skippedResult: SKIPPED_BANNED_RESULT }
+        }
+        if (await shouldSkipForUnsubscribe(allowed)) {
           return { index, data: null, skippedResult: SKIPPED_UNSUBSCRIBED_RESULT }
         }
-        return { index, data: processEmailData(email), skippedResult: null }
+        return { index, data: processEmailData(allowed), skippedResult: null }
       } catch (error) {
         return {
           index,