I was facing with a problem to send email from an Exchange Server 2010 to another one in a different location.
The error was, on the connector:
451 4.4.0 qurey failed the error was nonexistent domain
Trying to ping the remote server it wasn't resolved.
In the DNS server there wasn't the relative host.
In this case you can create an alias on DNS or, on the origin server modify:
C:\Windows\System32\drivers\etc\hosts
And add the following line:
192.168.X.Y servername.domain.zzz
