I have a similar set-up where I have a machine with two network cards on separate connections - one business and one residential connection.

The business connection is on local ip 192.168.0.2 and the residential connection is on 192.168.1.2

Xeams is being used a proxy and everything is fine but outgoing mail sometimes does not get delivered because Xeams tries to send it out on the residential IP (which is RBL blocked because it's residential). 

I followed the instructions at http://www.xeams.com/app?operation=forum&st=viewOneArticle&id=15244 adding outbound.smtp.binding.ip=192.168.0.2 in the server.properties file in $INSTALLDIR\config folder and restarted xeams.  

In the xeams log I have the following entry - 

ERROR smtp.b - Unable to bind to 192.168.0.2 for sending out-bound email. Connection timed out: connect

Understandably, some mail is still sitting in the outbound folder. 

I wasn't supposed to put the public IP address in the file was I?    Should I restart the server?   Or is there something else you think I could try to get this work?

Thank you in advance for any suggestions. 

Xeams acts as an SMTP client when sending emails out. A connection time out occurs can occur due to network connjection. How many emails do you have in your Outbound Queue and do they eventually get sent out?

Off course rebooting the machine will most likely solve this issue but try doing netstat to see how many open TCP/IP connections you have. It is also possible that too many sockets have already been created on the machine. Netstat should tell you that.