Here is an odd problem, We are upgrading our Exchange 2007 server to a 2013 server, we have most of the problems sorted out and most things are working.
basically the 2007 server is fully functional and can send emails to users whom reside on the 2013 server, but the 2013 server can only send mail during a reboot, if you send an email it sits in the queue until the server is restarted then it sends them all out at once and proceeds to stop sending them.
The 2013 sends through the 2007 server as a smart host for now (until we fully move to the 2013 server), this happens to both internal and external destinations.
The error that the queue shows while the messages are stuck in the queue on the 2013 is 441 4.4.1 (Socket Error)
My next steps in debugging this issue are to see which service specifically (if any) need to be restarted for this to happen, or if it only happens on a full server reboot. I'm thinking its another service on the server blocking the connections, Wanted to see what you guys thought.