I am currently experiencing an issue sending email to one specific domain. We are running Exchange 2007 (recently migrated from 2003). We are able to successfully send email both internally and externally to any other domain. The emails are queued in a DnsConnectorDelivery type queue with no Last Error message.The server is able to resolve the MX record correctly. The SMTPSend Log reveals the following:
2009-10-21T06:37:47.265Z,SMTP to Internet,08CC201AD304F254,0,,x.x.x.x:25,*,,attempting to connect 2009-10-21T06:37:47.281Z,SMTP to Internet,08CC201AD304F254,1,18.104.22.168:3544,x.x.x.x:25,+,, 2009-10-21T06:47:48.038Z,SMTP to Internet,08CC201AD304F254,2,22.214.171.124:3544,x.x.x.x:25,-,,Remote 2009-10-21T06:47:48.038Z,SMTP to Internet,08CC201AD304F254,0,,y.y.y.y:25,*,,attempting to connect 2009-10-21T06:47:48.054Z,SMTP to Internet,08CC201AD304F254,1,126.96.36.199:13695,y.y.y.y:25,+,, 2009-10-21T06:57:48.436Z,SMTP to Internet,08CC201AD304F254,2,188.8.131.52:13695,y.y.y.y:25,-,,Remote
...with x.x.x.x and y.y.y.y being the correct first and second MX records for the domain.
From my desktop (but a different external IP address), I am able to Telnet into x.x.x.x:25 and y.y.y.y:25 and send an email. When attempting to Telnet from the exchange server, it just waits after issuing the 'OPEN x.x.x.x 25' command. I am able to Telnet to other SMTP servers from our Exchange server successfully.
I'm working with and admin on the other domain to determine if our IP is somehow blacklisted, but is there anything else that would cause these symptoms?