i am using RHEL5.i configured posfix.
domainname=example.com
hostname=server1
when i send the mail to user@domain.com then the error is present
___________________________________________________________
X-Original-To: babu@server1.example.com
Delivered-To: babu@server1.example.com
Date: Tue, 17 Mar 2009 18:30:57 +0530 (IST)
From: MAILER-DAEMON@example.com (Mail Delivery System)
Subject: Undelivered Mail Returned to Sender
To: babu@server1.example.com
Auto-Submitted: auto-replied

[-- Attachment #1: Notification --]
[-- Type: text/plain, Encoding: 7bit, Size: 0.5K --]

This is the mail system at host server1.example.com.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to <postmaster>

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

-N +- 1/1: Mail Delivery System Undelivered Mail Returned to Sender -- (42%)


_________________________________________________________

i edit the /etc/mail/local-host-names file like this
_________________________
example.com
______________________


but the same error is coming. how to solve this problem. help me.

Check your maillog for files and check the logs on the receiving server for errors as well.

- Arch