non-delivery notification after change hard drive

[kilg]

Hi!
1. I have one hard drive mounting on /opt/zimbra for zimbra's server.
2. free space on this hard drive was left.
3. I mount new bigger hard drive and copy files from old hard drive with rsync.
then change hard drive and start zimbra.
all was ok, but same user have a problem. everybady who send this problem users mail, everybady receive sender non-delivery notification, but mail was sended saccessfuly.
sender non-delivery notification:
--------------------------------------------------------------
This is the mail system at host mail1.mydomain.my.

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.

The mail system

<user@mydomain.my>: mydomain.my

Final-Recipient: rfc822; user@mydomain.my
Original-Recipient: rfc822;user@mydomain.my
Action: failed
Status: 5.0.0
Diagnostic-Code: X-Postfix; mydomain.my
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I in doubt that the problem is due to chamge my hard.
can everyone help my?
notice: problem users have alias. and in "non-delivery notification" use alias name, but mail was send to canonical name.