I have a customer who recently had an issue with email delays from comcast to their own exchange server - no apple products involved anywhere - and it was at least in part because the comcast email server was on several blacklists.

I know what the problem is!! They are using their ISP's email service!!!!

I've been having this issue with my Comcast account forwarding to me.com:

**This is an automatically generated Delivery Status Notification. *****

Delivery to the following recipients is still underway after 13.7 hour(s):

** xxxxxx@me.com

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

Reporting-MTA: dns; qmta12.westchester.pa.mail.comcast.net [76.96.59.227] Received-From-MTA: dns; imta19.westchester.pa.mail.comcast.net [76.96.62.15] Arrival-Date: Tue, 06 Dec 2011 18:44:30 +0000 Final-recipient; xxxxxxxx@me.com Action: delayed Status: 4.1.1 Diagnostic-Code: smtp; 421 Too many recipient errors, try again later. Contact dotmacadmin@apple.com if you feel this is in error. Last-attempt-Date: Wed, 07 Dec 2011 08:23:45 +0000

Who still uses an ISP POP3 email service when there are much better options out there?

But it's FREE!! ...yeah, so is everything else.

Here's a 29-page thread on the Best Buy forums related to people whose iTunes gift codes were filtered out by Apple's spam filters. Almost all the people on the thread verified that they had the code sent to a mac.com or me.com address. A week after my purchase, the code finally showed up in my me.com account. The headers on the message indicated that it was sent about 10 minutes after I ordered it and had been been flagged as spam by Apple's filters.

While Best Buy's customer service was horrible, the issue was caused by Apple's overzealous spam filters. The vast majority of people who do not use MobileMe or iCloud received their gift codes within a half hour.

I had trouble with an email from a Verizon.net address. An 8 MB video file wasn't delivered until 3 hours after it was sent.