I have two internal email servers (ExchSrv1 [Exch 2003] and ExchSrv2 [Exch 2007]). ExchSrv1 is my 'bridge' server that excepts emails from our Barracuda device. The Barracuda device is excepting all inbound SMTP traffic. Issue------ Inbound email is coming through Barracuda and then being delivered to ExchSrv1. For those users that are located on Srv1, email is delivered. For those users on Srv2, the email is being 'queued' and is not being delivered. Internal email that is being sent from Srv1 to Srv2 is working fine.
Recent Changes----- I've upgraded to a different firewall which is no longer performing DNS Lookup itself. I've had to change my internal 'forwarders' to communicate to my ISP DNS server for other traffic. In testing, I had to remove my FW's internal interface from ExchSrv1 SMTP Vir Server properties and insert my ISP DNS server. I unfortunatly didn't realize that email from Srv1 to Srv 2 had stopped. I then added an internal DNS ip address in the SMTP Virtual Server setting, now, 'internal' email can flow between the to server.
What am I missing to allow email from the outside to flow from ExchSrv1 to ExchSrv2. Can anyone reply with proper DNS setup. 1.) What DNS server should be listed in the SMTP Vir Server on ExchSrv1, ExchSrv2 (i.e, internal DNS versus external DNS)
I see the emails being logged on Srv1; however, I don't see the emails being logged on Srv2. I'm guessing since they are never leaving Srv1, there is nothing to log!!!
I can send internal email from Srv1 to Srv2 and vice versa. Its the inbound 'internet' email that is being queued on Srv1.
Also, when I send email from Srv1 to Srv2, it takes several minutes. If I go into the connector on Srv1 and tell it to 'force connection', the email show up.
After hours of troubleshooting, I decided to contact Microsoft because nothing I was coming across was resolving the issue. Upon dealing with MS for hours, we discovered what the problem was. As simple as it seems, I had run out of disk space where the queueing folder was located. Since it did not have enough space to except the incoming emails, my first email server simply held the email until it was resolve. Once free space was made available, the queue emptied. As simple as it was, I was thrown off track a bit. Becuase I was able to pass email from Srv1 to Srv2, I didn't realize that the queuing folder was having a problem. It was a learning process... Thank you all for helping me troubleshoot this issue.
Could have been identified if you tried a telnet from srv1 to srv2.. like you say, if it was disk space issue, while telnetting or after issuing a MAIL FROM, it would have errored out with 'Insufficient System resources'! <backpressure>
I'm presuming it would have failed at MAIL FROM, cos internal mail was working and external was not. App logs on SRV2 would also have thrown up something relevant!!