As of a couple of days ago our Exchange 2007 server started delaying outbound emails to external recipients for about 2 days. However, we can receive emails from external email address outside our LAN with no problems. We can send emails within our LAN with no problems... inbound and outbound have no problems. There are about 78 messages in the Exchange Queue Viewer Tool. I get this error mesage in the Queue Viewer: 451 4.4.0 Primary Target IP Address responded with :"421 4.2.1 unable to connect." Emails are to various different domains. It seems that they eventually go through... but like I said it seems to take a least 48 hours. There was new sonicwall firewall installed last week as well... TZ 210 Wireless-N .... could this be causing the issue?

As of a couple of days ago our Exchange 2007 server started delaying outbound emails to external recipients for about 2 days. However, we can receive emails from external email address outside our LAN with no problems. We can send emails within our LAN with no problems... inbound and outbound have no problems. There are about 78 messages in the Exchange Queue Viewer Tool. I get this error mesage in the Queue Viewer: 451 4.4.0 Primary Target IP Address responded with :"421 4.2.1 unable to connect." Emails are to various different domains. It seems that they eventually go through... but like I said it seems to take a least 48 hours. There was new sonicwall firewall installed last week as well... TZ 210 Wireless-N .... could this be causing the issue? Sure sounds like a firewall/network issue.

Hi Chris, I agree with Andy. Check for Firewall: I suggest you check the configuration on your firewall (if possible, disable it to have a try). Check for Network: <1> You can use https://www.testexchangeconnectivity.com/ to do an Outbound email test, and paste the related information in your next post. <2> Use Mail Flow Troubleshooter, see if we can get any related information. Mail Flow Troubleshooter in Exchange Troubleshooting Assistant (ExTRA) - A closer look http://blogs.technet.com/b/exchange/archive/2006/08/07/3394688.aspx Thanks, Evan Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.