Thanks. That gets me closer.
Given an email address, if I know the DNS server for its domain (which I can
get in code since I have written code to do whois), then the code in the
Vb.net project download you suggested provides a way to get the email server
associated with that email address.
However, that all depends on using a dll packaged with the code --
DNSObjects.dll. What I would really like to see is the code that created
that dll, since that is where the work is done. And I don't want to use a
dll in my project.