Exchange unable to relay mail outbound

Question

I have some users configured in Exchange 2003 (delivery options tab) to forward mails to their external address.

This was working fine until today. The mails are being held up in the SMTP queue folder. I am able telnet the addresses (e.g. google.com) at port 25 from the server. Any reason why the mails are held up? Other emails are going out. It's only the mailboxes configured to forward the mail out to the public email addresses.

I also did the following

1. Check event logs for errors. Nothing.
2. Checked my domain on blacklists. Nothing.

Any idea?

Answer 1

The queue viewer will tell you why Exchange feels like it's unable to deliver. Running a sniffer and watching the traffic generated after forcing a queue to retry might give you some insight, too. Failing that you can crank up diagnostc logging, too. See http://support.microsoft.com/kb/823489 for details about the queue viewer and diagnostic logging.