We have CEntOS 6.3 on DELL server. WE try to use following mail command but failed. This command perfect work on CentOS 5.X. $ mail -s "test..." user1 at sun.com -- -f NoReply at App.MD.gov test . EOT $ /home/app/oracle/dead.letter... Saved message in /home/app/oracle/dead.letter problem come from "-- -f NoReply at App.MD.gov". But it work correctly on CentOS 5.x. Anyone know how to fix it? Thanks