Subject: Undelivered Mail Returned to Sender
From: [email-masked] (Mail Delivery System)
To: [email-masked]
Date: Thu, 12 Mar 2015 10:51:57 -0400 (EDT)

This is the mail system at host lb-ob1.listbox.com.

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 example.gov[123.4.5.67] said:
    554 Service unavailable; Client host [208.72.237.4] blocked using
    bl.spamcop.net; Blocked - see http://www.spamcop.net/bl.shtml?208.72.237.4
    (in reply to RCPT TO command)