I receive so many bouncing e-mails like this in reply to messages allegedly sent out from accounts that do not even exist. I doubt there might be a virus or spamware in the system or someone is using the server to relay e-mails. I have Postfix 2.6.6 but I'm not sure how to proceed!
Thanks for your help
OS: Centos: 6.5, webmin 1.730
This is the mail system at host mail.xdomain.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.
The mail system
<firstname.lastname@example.org>: data format error. Command output: shredl108: Mailbox
does not exist