Someone send me an email and I can't receive it on .me

It's impossible to say without more information. Perhaps it included an attachment that contained malware, and was filtered out by a server between you and the sender. Perhaps it looked a lot like junk mail and was caught by a server's spam filter. Perhaps it was mis-addressed. Perhaps the sender's server had a problem. Perhaps someone who shouldn't has access to your e-mail account and deleted the message before you saw it. The possibilities are nearly endless, especially for a one-time occurrence of a missing message.

Lately both my husband and I have been told my our kids and friends that many routine emails sent ot our .me addresses have vounced back to the sender as undeliverable. They reach us fine at gmail or isp addresses, they are not spam.

A friend sent me these headers: ( I changed the actual email addresses before the @ sign)

From: Mail Delivery System < mailer-daemon@comcast.net>
Date: August 8, 2013 4:31:26 AM PDT
To: xyz@comcast.net
Subject: Delivery status notification

This is an automatically generated Delivery Status Notification.

Delivery to the following recipients is still underway after 6.4 hour(s):

* abc@me.com

Will keep trying and contact you if the message can't be delivered permanently.

Reporting-MTA: dns; qmta10.emeryville.ca.mail.comcast.net [76.96.30.17] Received-From-MTA: dns; omta10.emeryville.ca.mail.comcast.net [76.96.30.28] Arrival-Date: Thu, 08 Aug 2013 05:05:54 +0000 Final-recipient: rfc822; abcf@me.com Action: delayed Status: 4.1.1 Diagnostic-Code: smtp; 451 4.5.3 No more transactions allowed. Last-attempt-Date: Thu, 08 Aug 2013 11:31:26 +0000