Hi all. I am trying to troubleshoot a strange issue with one of our client's Small Business Server - 2003 and 100% up-to-date with all SP's and updates. Users keep getting strange bouncebacks and undeliverable mail lately such as:
ContactName on 24/01/2008 5:56 PM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<mailgate.domain.com #5.5.0 smtp;501 <E>: sender address must contain a domain>
I work with alot of SBS 2003 sites but this is a new one on me!! Any help greatly appreciated.