Inbound mail delayed from Exchange 2007 to Messagelabs servers
Mail is randomly being delayed from Exchange 2007 server for several hours. Initially there were DNS lookup errors in the Exchange SMTP protocol logs. The Exchange transport was changed to utilize an external DNS server and the errors went away.
Now the sender get a message delayed message after 4 hours and eventually the message gets delivered. No errors appear in the SMTP send connector logs.
Mail flows properly to all outside domains. The only delays are to Messagelabs servers.
This is an urgent issue. What can I do to resolve this problem?