I've got several Exchange 2007 servers communicating over WAN, distributed ove branch offices. Communication runs normally to all Exchange server, untill the public folders are syncing. I see hierarchy mails and other publicfolder mails stuck in the queue for the branch office and vice versa.
When I run the mail-flow troubleshooting tool, it confirms the backed up queues and proceeds with troubleshooting. It comes up with two problems, the MTU values and BDAT command not supported. This is the same on all Exchange servers.
When I suspend the public folder mails and retry the queue, all other emails are sent. In the queue viewer the last error for these problematic mails is: 421 4.3.2 System not accepting network messages.
I've tried new receive connectors, locked in only for the branch office exchange servers, the same error message occurs. I've changed the send connector to turn off ESMTP, to try and solve the BDAT error, no go either.
You guys got any ideas?