expose imap username field (#15866)

Had an edge with a customer where they had a custom username.

packages/twenty-front/src/modules/settings/accounts/components/SettingsAccountsConnectionForm.tsx

@@ -120,6 +120,23 @@ export const SettingsAccountsConnectionForm = ({
             )}
           />
 
+          <Controller
+            name="IMAP.username"
+            control={control}
+            render={({ field, fieldState }) => (
+              <SettingsTextInput
+                instanceId="imap-username-connection-form"
+                label={t`IMAP Username (Optional)`}
+                placeholder={t`john.doe`}
+                type="text"
+                value={field.value || ''}
+                required={false}
+                onChange={field.onChange}
+                error={fieldState.error?.message}
+              />
+            )}
+          />
+
           <Controller
             name="IMAP.password"
             control={control}

packages/twenty-server/src/engine/core-modules/imap-smtp-caldav-connection/services/imap-smtp-caldav-connection.service.ts

@@ -31,7 +31,7 @@ export class ImapSmtpCaldavService {
       port: params.port,
       secure: params.secure ?? true,
       auth: {
-        user: handle,
+        user: params.username ?? handle,
         pass: params.password,
       },
       logger: false,

packages/twenty-server/src/modules/messaging/message-import-manager/drivers/imap/providers/imap-client.provider.ts

@@ -1,5 +1,6 @@
 import { Injectable, Logger } from '@nestjs/common';
 
+import { isNonEmptyString } from '@sniptt/guards';
 import { ImapFlow } from 'imapflow';
 import { ConnectedAccountProvider } from 'twenty-shared/types';
 import { isDefined } from 'twenty-shared/utils';
@@ -88,7 +89,9 @@ export class ImapClientProvider {
         port: connectionParameters.IMAP?.port || 993,
         secure: connectionParameters.IMAP?.secure,
         auth: {
-          user: connectedAccount.handle,
+          user: isNonEmptyString(connectionParameters.IMAP?.username)
+            ? connectionParameters.IMAP?.username
+            : connectedAccount.handle,
           pass: connectionParameters.IMAP?.password || '',
         },
         logger: false,