Subject: Undelivered Mail Returned to Sender

From: [email-masked] (Mail Delivery System)
Date: Tue, 27 Nov 2007 01:41:13 +0900 (JST)

This is the Postfix program at host mail.begi.net.

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 Postfix program

<[email-masked]>: host /var/lib/imap/socket/lmtp[/var/lib/imap/socket/lmtp]
    said: 550-Mailbox unknown.  Either there is no mailbox associated with this
    550-name or you do not have authorization to see it. 550 5.1.1 User unknown
    (in reply to RCPT TO command)