Laptop getting hundreds of delivery status notification (failure) that are spam

My user has a Google account for SMTP and a prodigy.net.mx account for POP. He is getting these hundreds of delivery status notification (failure) that contain a porn link. (Never clicked on the link but the wording is porn).

Any ideas on how I can stop this?

Here's what was in one of the emails, minus the bad language and with an xxx before any email addresses:

From:
"Daniel Mcintyre" <xxx@prodigy.net.mx>

Date:
11/11/2014 3:48 PM
To:
xxx@yahoo.com

X-IronPort-AV:
E=Sophos;i="5.07,362,1413262800"; d="scan'208,217";a="6537892"
Received:
from nlpiport22.prodigy.net.mx ([148.235.52.109]) by nlpiport16.prodigy.net.mx with ESMTP; 11 Nov 2014 16:48:10 -0600
X-IronPort-Anti-Spam-Filtered:
true
X-IronPort-Anti-Spam-Result:
AoNaADuRYlREkXOMPGdsb2JhbAANNRqCSIEaWQGDb4l3FapQAgMGgykBAVYMP4Efi3kJgWWHSwKBNwEBAQEBBgEBAQEUJIVbAQIbNDSIezi3D4JmlRCGOop3hDUFkjFjg3CJEpY2AQEBBwEBAQEBgiZqgksBAQE
Received:
from s0106602ad090a6ee.cg.shawcable.net (HELO [192.168.243.237]) ([68.145.115.140]) by nlpiport22.prodigy.net.mx with ESMTP; 11 Nov 2014 16:48:10 -0600
Content-Type:
multipart/alternative; boundary="===============4923497437629272293=="
MIME-Version:
1.0
Message-ID:
<54629247.999005@prodigy.net.mx>

He uses Thunderbird as his email client.