Implement procmail filtering. Sendmail plays the part of the mail delivery
agent, and for a single mail account, procmail filtering suits better.
For mails from all other domains, you may just want to delete them, instead
of sending a bounce message.
I have a useraccount with email address info(a)unitech.com and
I want to setup my sendmail in such a way that it will accpet mail to
info(a)unitech.com only if
sender's domain is unitech.com
For rest of the world , it will be bounced back for all other