email routing should apply to a specific domain right?
email routing should apply to a specific domain right?

mydomain.com I can't have another MX record. So I route a mail from mail@mydomain.com to mail@secretdomain.com. Now if I want to answer that mail, is it possible to use mail@mydomain.com as the sending address, so no one sees the secretdomain.com address?mydomain.com is setup properly, sure.

mydomain.commydomain.commail@mydomain.commail@mydomain.commail@secretdomain.comsecretdomain.com