I have a strange issueon an Exchange 2003 Server on Windows 2003 SBS Server. All was good untilour FQDN changed. What I did was run SBS's Internet Connection wizard to change our FQDN. I added SMTP addresses for each user and made the new addresses the primary addresses. I go to DNSReports.com and run our FQDNand it comes back clean, ( no issues). The server OS has SP2, Exchange Server has SP2. Life is good with one exception. I am unable to receive email from 2 different domains. Interestingly both domains are two letter domains, just a coincidence probably.We do not receive email fromusers at these two, two letter domains. They do not receive a NDR and there is nothing in the event logs of our Exchange server or ISA server to indicate an issue. I suspected an issue with our Trend Micro Client/Server Messaging Suite for SMB (SPAM/AntiVirus)which has a SPAM filter. I disabled SPAM filtering but we still do not receive these emails. The Trend Micro product has a real time monitor where you can see emails as they come into the system. I have watched this and have seen the domains in question appear in the monitor so I know the emails in question are getting here and likely being processed by Trend Micro. The Exchange message tracking utility cannot find any record of them. I called Trend Micro and their techs suggestionis toshut down SPAM and Anti-Virus on the Exchange server but I can't afford to take that chance. The only solution I can think of is to uninstall and reinstall the Trend Micro product. Has anybody got any other ideas?