Subject: Undelivered Mail Returned to Sender
From: [email-masked] (Mail Delivery System)
To: [email-masked]
Date: Tue, 6 Sep 2011 14:35:52 +0100 (BST)

This is the mail system at host admin1.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 mail.test2.net[217.194.212.245] said: 554
    Sending address not accepted due to spam filter (in reply to MAIL FROM
    command)

Subject: foo
From: Fred Bloggs <[email-masked]>
To: john smith <[email-masked]>
Date: Tue, 6 Sep 2011 14:34:17 +0100

HTML