Enabling masquerade in sendmail

I have never worked with sendmail before.  In the past it was something that just worked, and I never had to tweak it.  However, now I need to enable masquerade. 

There is one particular server where the developers need to be able to send mail to themselves.  The mail that is being sent out is being blocked by the income mail server.  The mail being blocked goes out as user@<host>.<domain>.  If I can change the outgoing address simply as user@<domain> then the mail will go through. 

(I was interrupted while working on this posting, and accidentally posted it without finishing it.)