We recently migrated to a new AD domain with a new Exchange 2013 box. Prior to that we were on Exchange 2007 in a different domain. We use postini for our spam/virus filtering.
Since we've moved to the Exchange 2013 solution, we have started having issues with some (not all) Google apps hosted domains. The firewall and IP of the server stayed the same regardless of the change. I looked into routing all of our outbound mail (or just specific domains) through Postini to help with this issue, but their instructions work for 2007 and 2010 - not 2013. I tried setting it up with their directions, but modifying it for 2013, but that was a big failure. We are seeing message delayed codes returned.
Remote Server returned '400 4.4.7 Message delayed'
I did some research through Google Apps, but the only thing I found is a server reboot, which does nothing.
I have it working right now by routing everything for these Google Apps hosted domains by creating a separate send connector that routes through smtp.google.com as a smart host (using a gmail ID and password) but that's only going to work for so many messages before it bombs, and we won't even get a notification.
Any suggestions?