My Comcast/Charter email is unreliable

When I talk with Comcast Support, they tell me it is Charter’s problem. When I talk with Charter Support, they tell me it is Comcast’s problem. I’ve done a number of tests (described below). I think (although I am far from certain) that it is a Comcast issue.

Has anyone else experienced this problem? Can anyone suggest why I am experiencing it?

Sorry for the length of this post. I’ve been doing tests for days. I’ve summarized those tests that I think contribute to characterizing the problem.

Background

I have two ISPs, Comcast and Charter. I have Comcast in Portland and Charter in Cannon Beach.   I have mail accounts with Comcast. I have mail accounts with Charter.

 

Here is the problem.

When I send mail from my Charter account to my Comcast account, it does not arrive. Comcast receives mail from all other sources. Comcast does not receive mail from Charter.

Before Testing

I changed the passwords on all my Comcast accounts. I changed the passwords on all my Charter accounts. I cleared the cache and cookies from my browser and then I log onto the servers. My issue is not dependent on my browser and OS. I see the same problem with Edge on win10, Edge on win11, Firefox on Ubuntu, Safari on IOS.

 

Here is how I tested.

I send/receive mail directly on the Comcast and Charter websites.  I am not using an email client (although when I do, I see the same issue). So there is no 3rd party application involved. My primary charter account is <primary charter account>.

Mail from charter to comcast does not arrive at comcast

Mail from comcast to charter does arrive at charter

Mail from charter to Gmail does arrive at Gmail

Mail from Gmail to charter does arrive at charter

Mail from charter to comcast does not arrive at comcast

I log into www.charter.net as <primary charter account>.

I send mail to <primary comcast account>. I do not get an error message.

I see the mail I sent appear in the Sent folder on www.charter.net.

I log onto www.comcast.net as <primary comcast account>.

I do not see the mail I sent from <primary charter account>. It never arrives.

 

Mail from comcast to charter does arrive at charter

I log onto www.comcast.net as <primary comcast account>.

I send mail to <primary charter account>.

I see the mail I sent appear in the Sent folder on www.comcast.net.

I log onto www.charter.net as <primary charter account>.

I see the mail I sent from <primary comcast account> arrive.

 

Mail from charter to Gmail does arrive at Gmail

As another test, I log onto gmail.com as <Gmail account>. I send mail from <primary charter account> while on  www.charter.com in another window. The mail arrives at <Gmail account>.

 

Mail from Gmail to charter does arrive at charter

As another test, I log onto gmail.com as <Gmail account>. I send mail from <Gmail account> to <primary charter account>. On www.charter.net I see the mail from <Gmail account> arrive.

Summary

I am at a loss. The Comcast/Charter connection is unreliable enough to be dangerous. If someone (a business, for example) has a Charter email address and records my connection as a Comcast email address, I can lose valuable information. I would never see that information.

It is possible that the problem only exists with my Comcast/Charter accounts. I doubt that because there is nothing special about my Comcast/Charter accounts.