Subject: Undelivered Mail Returned to Sender

From: [email-masked] (Mail Delivery System)
Date: Tue, 23 Sep 2008 04:52:44 +0200 (CEST)

This is the mail system at host mx-2.tng.de.

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

<[email-masked]>: host mx-1.tng.de[213.178.66.80] said: 551 5.1.1
    <[email-masked]>: Recipient address rejected: undeliverable address: host
    195.244.232.98[195.244.232.98] said: 550 5.1.1 User unknown (in reply to
    RCPT TO command) (in reply to RCPT TO command)