I am running Exchange 2003 SP2 on Server 2003. Suddenly I received an error on my virtual smtp server queue "connection dropped due to protocol sink error". I have run the SMTPDiag tool and everything is OK except for the error "dns server did not return a valid soa record". I have checked my DNS settings, servers etc all seems to be OK. There were no changes made to either DNS or Exchange server before this error occurred. Internal mail is OK and external mail comes through fine. Can anyone offer any ideas?? thanks.

Hi, First, please let me know if you have installed GFI mail essentials and some third party Anti-Virus software on the server. If so, please disable their service and test the issue again. If the issue persist, I suggest uninstalling GFI mail essentials temporary and restart server to test the issue. You can reinstall it later. If the issue persists, please clear DNS cache to test the issue: Click start, run, type dnsmgmt.msc, choose the server and select clear cache. Meanwhile, you can try to create another SMTP virtual server to test the issue. Please also let me know if there is other related event log. I await your reply. Regards, Elvis

Hi Elvis, Thanks for your reply. I am not running Antivirus - although come to think of it, I had installed GFIMail Essentials to test around the same time that this problem started. I have already uninstalled it though and problem still persists.As SMTPDiag pointed to the records not being the same on the DNS server (which is my Internet ADSL router, inside port) as on my internal DNS server (Windows 2003) which I thought was strange, didn't think the ADSL router kept these records or acted as DNS server, anyway, I reset the router after many other attempts of trying to update the records (which I could not find on the router) and am now having issues trying to make a connection to my ISP - they are currently looking at it at the moment. Will let you know how I go. Can you explain why the ADSL router would be keeping DNS records? Thanks