Bounce message's domain

[SysAdm]

 Hi all.

 Situation: I have {domain1,domain2,domain3}.com, and every one of them is virtual. 
Someone sends a message to [EMAIL PROTECTED], and the bounce comes from 
mailer-daemon@`hostname` instead of coming from [EMAIL PROTECTED] Quick fixes 
anyone?

 Best of regards, and TIA for any help.for any help.