Mac.Com Addresses Fail in iCloud?

While I'm continuing to get my mail, each new email comes with an additional error email indicating that my vaild @mac.com email address is NOT valid. What gives?

Here's the message:

This report relates to a message you sent with the following header fields:

Message-id:
<15013-512-DBNY4S-PROZ3D-OJ1O4A-LJHJ5YH-0VO0QZ-H-M2-20130307-c42c1c05d0d414@e-dia log.com>
Date: Thu, 07 Mar 2013 10:26:52 -0500
From: Dell <Dell@Dellhome.usa.dell.com>
To: jhsayers@mac.com
Subject: Upgrade your TV and save up to $200

Processing errors occurred during delivery:

Recipient address: jhsayers@mac.com
Reason: Error in sieve filter: Notify mailto: recipient is not a valid address

Delivery processing continued in spite of these errors.