Subject: Undelivered Mail Returned to Sender
From: [email-masked] (Mail Delivery System)
To: [email-masked]
Date: Mon, 30 Jan 2012 10:50:21 +0000 (GMT)

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 service101.mimecast.com[91.220.42.51] said: 554
    email rejected due to security policies - MCSpamSignature.sa.5.6 (in reply
    to end of DATA command)

Subject: foo
From: Fred Bloggs <[email-masked]>
To: John Smith <[email-masked]>
Date: Mon, 30 Jan 2012 10:30:52 +0000

HTML