We have a motley collection of COTS business applications with limited SMTP capabilities.  These applications generate e-mail messages to customers on behalf of our employees.  For instance an application will send a confirmation or invoice to a customer with a specific account manager as the from address.  All of these COTS applications use the same IIS SMTP server to send out of our network to the world.  I'd like to be able to modify some of these messages as they go out.  For example add CC, add receipt requests, append legal disclaimers, etc, all details that the COTS applications don't support.

Is it possible to make the basic SMTP server append header?  Would an Exchange SMTP be able to do this?  Anyone know of any other SMTP relay solutions that can modify headers?

An Exchange server could certainly do some of those things: add CC, append legal disclaimer.

As for "etc." I don't know what other specific requirements you have?

I'm really only familiar with the Exchange implementation of SMTP so I don't know what "basic" SMTP allows natively (i.e. with ANY messaging system).

Otherwise, do you know if COTS would interact with Exchange? Can you contact the vendor?