feat: add email forwarding message channel (#19535)

## Summary

- Add email forwarding as a new message channel type, allowing users to
forward emails from addresses like `support@mycompany.com` into Twenty
- Inbound emails arrive via S3 (SES → S3 bucket), are polled by a cron
job, parsed, routed to the correct workspace/channel, and persisted as
messages
- Dedicated settings page at `/settings/accounts/new-email-forwarding`
where users provide their source email handle and receive a unique
forwarding address
- Forwarding channels bypass the IMAP/mailbox sync state machine — they
skip cron-driven sync, relaunch, and message-list-fetch lifecycle stages
- Forwarding address section shown at the top of the Emails settings
page so users can find/copy their addresses after initial setup
- Tab names for forwarding channels display the user-provided handle
(e.g. `support@mycompany.com`) instead of the internal routing address
- Shared utilities extracted from IMAP driver: `extractThreadId`,
`extractParticipants`, `extractAddresses` to avoid code duplication
- Uses the existing S3 bucket (STORAGE_S3_*) with `inbound-email/`
prefix — no separate bucket needed
- Feature gated behind `isEmailForwardingEnabled` client config
(requires `INBOUND_EMAIL_DOMAIN` + S3 storage)

## New backend modules

- `InboundEmailS3ClientProvider` — lazy-initialized S3 client using
existing storage config
- `InboundEmailStorageService` — S3 operations (get, move to
processed/unmatched/failed)
- `InboundEmailParserService` — RFC 822 parsing via `postal-mime`,
builds `MessageWithParticipants`
- `InboundEmailImportService` — orchestrates download → parse → route →
persist → archive
- `MessagingInboundEmailPollCronJob` — polls S3 `incoming/` prefix,
enqueues import jobs
- `CreateEmailForwardingChannelInput` DTO — accepts user-provided
`handle`

## New frontend components

- `SettingsAccountsNewEmailForwardingChannel` — dedicated page with
handle input form + forwarding address result
- `SettingsAccountsEmailForwardingSection` — forwarding address list on
the Emails settings page
- `useConnectedAccountHandleMap` — shared hook for account ID → handle
lookup
- `useCreateEmailForwardingChannel` — mutation hook accepting handle
parameter

## Test plan

- [x] 17 unit tests for inbound email import service (all outcomes:
imported, unmatched, loop_dropped, unconfigured, parse_failed,
persist_failed)
- [x] 16 tests for `computeSyncStatus` including EMAIL_FORWARDING cases
- [x] 11 tests for `extractEnvelopeRecipient` utility
- [x] TypeScript typechecks pass for both twenty-server and twenty-front
- [x] Lint passes for both packages
- [ ] Manual: create forwarding channel, verify forwarding address
generated
- [ ] Manual: send email to forwarding address, verify it appears in
Twenty

https://claude.ai/code/session_01KpyF6p4cUEnuaT4h8DP5Pm

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Copilot Autofix powered by AI <223894421+github-code-quality[bot]@users.noreply.github.com>
Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: neo773 <62795688+neo773@users.noreply.github.com>
Co-authored-by: neo773 <neo773@protonmail.com>

packages/twenty-server/src/engine/core-modules/client-config/client-config.controller.spec.ts

@@ -94,6 +94,7 @@ describe('ClientConfigController', () => {
         isGoogleCalendarEnabled: false,
         isConfigVariablesInDbEnabled: false,
         isImapSmtpCaldavEnabled: false,
+        isEmailGroupEnabled: false,
         calendarBookingPageId: undefined,
         isTwoFactorAuthenticationEnabled: false,
         allowRequestsToTwentyIcons: true,

packages/twenty-server/src/engine/core-modules/client-config/client-config.entity.ts

@@ -309,6 +309,9 @@ export class ClientConfig {
   @Field(() => Boolean)
   isImapSmtpCaldavEnabled: boolean;
 
+  @Field(() => Boolean)
+  isEmailGroupEnabled: boolean;
+
   @Field(() => Boolean)
   allowRequestsToTwentyIcons: boolean;
 

packages/twenty-server/src/engine/core-modules/client-config/services/client-config.service.spec.ts

@@ -171,6 +171,7 @@ describe('ClientConfigService', () => {
         isGoogleCalendarEnabled: true,
         isConfigVariablesInDbEnabled: false,
         isImapSmtpCaldavEnabled: false,
+        isEmailGroupEnabled: false,
         allowRequestsToTwentyIcons: false,
         calendarBookingPageId: 'team/twenty/talk-to-us',
         isCloudflareIntegrationEnabled: false,

packages/twenty-server/src/engine/core-modules/client-config/services/client-config.service.ts

@@ -4,6 +4,8 @@ import { isNonEmptyString } from '@sniptt/guards';
 import { isDefined } from 'twenty-shared/utils';
 import { type AiSdkPackage } from 'twenty-shared/ai';
 
+import { StorageDriverType } from 'src/engine/core-modules/file-storage/interfaces/file-storage.interface';
+
 import {
   AI_SDK_ANTHROPIC,
   AI_SDK_BEDROCK,
@@ -247,6 +249,10 @@ export class ClientConfigService {
       isImapSmtpCaldavEnabled: this.twentyConfigService.get(
         'IS_IMAP_SMTP_CALDAV_ENABLED',
       ),
+      isEmailGroupEnabled:
+        this.twentyConfigService.get('STORAGE_TYPE') ===
+          StorageDriverType.S_3 &&
+        isNonEmptyString(this.twentyConfigService.get('INBOUND_EMAIL_DOMAIN')),
       allowRequestsToTwentyIcons: this.twentyConfigService.get(
         'ALLOW_REQUESTS_TO_TWENTY_ICONS',
       ),