I am at a loss on this one I've tried everything that I can think of so hopefully someone will be able to assist.
We are running Exchange 2003 we also have a Barracuda Spam Firewall. During the weekend (of course) we had a power spike, while everything appeared to be ok something went wrong with our email system as we are not able to send mail outside of our network anymore. We are receiving mail just fine from all domains, but we cannot reply back to them.
This is the error we are getting:
email@example.com on 10/27/2008 12:44 PM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<EMAILSERVER #5.5.0 smtp;550 No such domain at this location (firstname.lastname@example.org)>
On the Barracuda the message log just gives a Invalid Domain error as the reason.
Steps I've taken:
I have reconfigured our firewall and bypassed the Barracuda sending all mail directly to the mailserver.
--This was successful we were able to send mail out but we got a very excessive amount of spam
Deleted and rebuilt the SMTP Connecter in Exchange 2003 setting up the Smart Host ensuring it's pointing to the Barracuda
Verified all settings with Barracuda to ensure that the Spam Firewall was configured correctly (my gut tells me that they missed something though due to the fact we can send out when we bypass the Spam Filter)
--We added the domains that send out from our mail server to the trusted domains
--Added the internal mail server IP address to Trusted IP's
--Mail is showing up on the message log on the Spam filter just not going anywhere after that.
I hope there is enough information here...logically it looks like the Barracuda is at fault, however maybe my brain is fried from looking at it trying to resolve the issue. Any help or suggestions would be greatly appreciated.