I have added an Exchange 2013 Server to my domain which already has 2 Exchange 2007 servers. Outgoing mail from the 2013 server gets stuck in the queue with the error
"Failed to connect. Winsock error code: 10060, Win32 error code: 10060, Error Message: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond xx.xx.xx.xx:25"
The Exchange 2007 server can still send mail out just fine. I have removed my smart-host from the mix temporarily to make sure that it wasn't them by creating a send connector that sends directly to the internet. Some messages will get through initially but the outgoing mail queue fills up quickly with those that do not get sent.
old286