Mercury doesn't discriminate on specific interfaces.  The greeting string will be the same, no matter what the local address of the connected socket is.  As far as I can tell, there's in fact no way to tell Mercury to do anything more than bind to specific addresses for use as server; client sockets are decided as usual by the OS according to address reachability (that's behaviour you can change in Windows itself if you've a mind, but by default it's based on the IP number of the destination).

Cheers,

Sabahattin

I have a Mercury setup that I have used for years now.

It has been working great.

I just recently added a second network card to the same computer.

This 2nd NIC has a different IP, and gateway.

The first NIC is attached to a DSL line from one ISP, and the 2nd NIC is attached to a different Fiber line from a differnet ISP. 

I am using this with 2 MX records - all pointing to the same instance of Mercury Mail.

Mercury is receiving mail just fine on both "lines" .

However, when Mercury sends it's initial "220 " helo on the 2nd NIC it looks like "220 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" instead of "220 domain.com"

everything otherwise seems to work.

Are you sure you are looking directly at the Mercury/32 system when you do this?  This really looks like one of those strings where a router is messing with the reply from the system.