I am hosting 3 domains in one server. For headers Return-Path,X-RocketMAILFROM and Received, sendmail puts canonical name of the server with correct usernames. For example if I send and email as user user1, these headers look like user1 at canonicalname.com. For user2 as user2 at canonicalname.com
DNS looks fine and I have in my hosts file the following, localhost localhost.localdomain canonicalname.com
***.**.***.**(serverís ip) domain1.com
***.**.***.** domain2.com
***.**.***.** domain3.com

Any help appreciated.