take into account mailbox in forward phase

email_handler.py

@@ -199,7 +199,10 @@ class MailHandler:
                 LOG.d("alias %s cannot be created on-the-fly, return 510", alias)
                 return "510 Email not exist"
 
-        user_email = gen_email.user.email
+        if gen_email.mailbox_id:
+            mailbox_email = gen_email.mailbox.email
+        else:
+            mailbox_email = gen_email.user.email
 
         website_email = get_email_part(msg["From"])
 
@@ -267,7 +270,7 @@ class MailHandler:
             LOG.d(
                 "Forward mail from %s to %s, mail_options %s, rcpt_options %s ",
                 website_email,
-                user_email,
+                mailbox_email,
                 envelope.mail_options,
                 envelope.rcpt_options,
             )
@@ -277,7 +280,7 @@ class MailHandler:
             msg_raw = msg.as_string().encode()
             smtp.sendmail(
                 forward_email.reply_email,
-                user_email,
+                mailbox_email,
                 msg_raw,
                 envelope.mail_options,
                 envelope.rcpt_options,

server.py

@@ -48,6 +48,7 @@ from app.models import (
     CustomDomain,
     LifetimeCoupon,
     Directory,
+    Mailbox,
 )
 from app.monitor.base import monitor_bp
 from app.oauth.base import oauth_bp
@@ -179,6 +180,7 @@ def fake_data():
     client2.published = True
     db.session.commit()
 
+    Mailbox.create(user_id=user.id, email="ab@cd.ef", verified=True)
     db.session.commit()