[tony17112acst]

Bill, thank you so much for all of that info! You are very generous!

Here's some more info - in the order in which you raise each item:

But first: I do not run a server. I have a company called Freehostia hosting my web and email for my domain and I need some expertise because Comcast is saying it's not their fault and Freehostia is saying it's not theirs and I don't know who's right. I'd like to nail down who's right so I can attack the right party to get this nightmare resolved.

the root cause might be DNS configuration by the owner of the destination domain (probably you), a secondary DNS cache somewhere, or Comcast.

Yes, I own the destination domain and Freehostia hosts both my website and email - I have never changed any DNS settings with them.

The important information which is missing in your post is everything after "Reason: Permanent Error." in the body of the DSN message... ...More about the cause is probably included in the body of the DSN message..

Unfortunately, what I posted is the entire text of all the DSN messages. Also, for a single email sent from a Comcast account, usually 3 "temporary error" DSN's are received before the "permanent error" is finally received (about 48 hours afterwards) and all of them have that very short message as the body with no extra info - just change the word from "permanent" to "temporary" for 3 prior DSN's before the permanent error one. Fortunately, my ISP is Comcast, so I can send myself messages and get the DSN's full info.

We can't tell from what you posted if it was a forwarding rule or a Comcast customer sending from their Comcast email account.

All test messages are either sent directly from MY Comcast SMTP account or 5 other friends and family's Comcast SMTP (tested and all failed).

An outgoing spam filter at Comcast is preventing some types of messages from being sent by their servers, a problem discovering a route to the destination address (such as if the MX records for your domain could not be found or were corrupted), or some other permanent addressing failure (such as your MX records pointing to a target IP which is blocked by Comcast or for some other reason is permanently unreachable).

Comcast tier 3 support swears they have no outgoing spam filters, but I find that very hard to believe. Also, I have never changed MX records, or any DNS settings as the entire domain (email and web) is hosted by Freehostia (all I did was point my registrar's name servers to my host's name servers).

This is where it gets weird (and this should tell you a lot):
* The problem started with my host 50Webs.com which hosted both my email and website for 10 years,
* Out of nowhere, beginning 4 weeks ago, anyone using Comcast's SMTP to send me email (hosted by 50Webs) were ALL failing when everyone else in the world were getting through,
* The failures all started on January 1st (4 weeks ago) with no changes to any of my setting for years and years (no TTL or DNS problems),
* 50Webs offers no support for their free services, and since Comcast said it's not their fault, I decided to change my web and email hosting to Freehostia,
* I set up my Freehostia account just ONE WEEK ago,
* To my utter amazement, Freehostia was having the exact same problem receiving Comcast emails!!!
* After much research, I found they are both part of the same company: Liquidnet,
* I own 3 domains, two were with 50Webs and the 3rd was just forwarded to one of the other two by my registrar,
* I now have the previously forwarded domain hosted at Freehostia for testing purposes for a solution.

So since I just created a hosting account with Freehostia only a week ago, I'm thinking it cannot be a DNS cache, TTL, MX CNAME or any DNS related problem - plus I never changed any of those settings in the 1st place.

2. The Comcast server found a reason not to send the message to the destination.

OK, That's the info I'm looking for, but how do you know for sure that Comcast's server decided not to send the message versus Comcast sending it and my email host rejecting it?

That's the info I need if I'm going to call Comcast back and tell them they're wrong for telling me they are sure their servers are passing it to Freehostia - I need to tell them WHY they are wrong. They are a huge disappointment so far. They went as far to tell me that their engineer observed the email being sent out of the servers (don't know what they checked).

Thanks! -Tony