I have a problem with a particular email address on the system. Everything works great when you send mail from any external address. Here is the example:
Sending via IMAP from user A@example.org to user B@example.org the mail is deferred with a message as follows:
451 4.0.0 Temporary message delivery failure try again (in reply to end of DATA command))
Now any other user is fine.. eg: C@example.org to A@example.org... So only B@example.org is having the issue.
Now if the users go through the web client everything works fine. This issue is only if IMAP is used....
Anyone have any ideas?