Mail routing from 2007 mailbox to 2010 Mailbox "Hub Version 14" Error
I've got a strange issue I'm hoping someone may be able to help with....
I've recently added an Exchange 2010 Server into my Organisation. I'm now co-existing with 2007 and 2010.
Everything appeared to be working smoothly... I could send mail to mailboxes between both servers and send mail externally from mailboxes on the 2010 Server.
Now, for what appears to be no reason, messages sent to a mailbox on the 2010 server (from a 2007 mailbox or external) now sit in the "Hub Version 14" Queue on the 2007 Server. There is no way to force this to send.
Eventually, I get the "451 4.4.0 DNS Query Failed. SMTPSEND.DNS.NonExistentDomain; nonexistent domain" error.
There is no delay EVER when sending mail from the 2010 Server.
Now the really funny thing is that every day at 19:40 the queue is cleared and the mail is delivered to the 2010 Mailboxes.
Any advice would be greatly appreciated.