Subject: Undelivered Mail Returned to Sender
From: [email-masked] (Mail Delivery System)
To: [email-masked]
Date: Wed, 11 Aug 2010 14:52:00 +0100 (BST)

This is the mail system at host server4.example.co.uk.

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.example.net[217.74.65.64] said: 550 5.2.1
    Mailbox not available / Konto niedostepne (in reply to RCPT TO command)

Subject: foo
From: Fred Bloggs <[email-masked]>
To: John Smith <[email-masked]>
Date: Wed, 11 Aug 2010 14:51:58 +0100

HTML