Help needed with possible DNS related issue with Comcast mail servers

[jerry47]

I just discovered the above problem yesterday. I just built an Intel NUC7i7 and installed Ubuntu 18.10 on it. Previously I installed 18.04 on an 10 year old laptop. It connected to comcast email via pop3 just fine two weeks ago. The NUC on the other hand did not. I don't believe this is a Thunderbird issue. First, I installed Thunderbird in a virtual environment on my Win 7 machine. Worked just fine connecting to port 995 using pop3. Second, I installed Evolution Mail on the NUC machine and it could not connect to comcast either. The error was "can not resolve mail.comcast.net". Now its looking like a DNS issue only for comcast mail only with Ubuntu. Third, I checked my laptop which has not been running for a couple of weeks and where Thunderbird was working it indeed had the same issue. I had not even updated it.

I discovered the same thing pinging on my windows machine that mail.comcast.net was redirected to imap.ge.xfinity.com. I used the host imap.ge.xfinity.com instead and Thunderbird grumbled about security and certificates. Ignored it and pop3 worked.

Since my Ubuntu install is just for evaluation purposes its not an issue for me. I just configured it IMAP. But I am very curious as to what's going on. We have two Win 7 machines, two iPads, two mobiles all using comcast pop3 without an issue even with the redirection. I was chatting with comcast on twitter for a couple of hours. He checked their archives and it revealed nothing. But he said they have very few customers using pop3 and very few using Linux. He does want me to contact him to log this issue as soon as I can find what the problem is exactly.

[1clue]

You know, at some point I decided that an ISP's mail server is not necessarily a great thing.

For one thing it only lasts as long as you have that ISP, so if you move to a place where that ISP does not exist, you lost your email address and probably your mail history.

Another issue is they seem to be more problematic than an independent mail provider.

I've started using several emails each from some third-party provider. At least one is a paid account NOT at a place like gmail or yahoo, and not linked to any of those places with any sort of forwarding.

The thing is, if you have a free account with ANY service on the Internet, you are not the customer. You're the product being sold to customers. If you pay, then you're the customer. Gmail, yahoo and every other free mail service, as well as any forum (including this one) gets significant value translating to money for the host.

That's not always a bad thing. Canonical, in maintaining Ubuntu and hosting this forum, gets customer support for and from the forum members. The good part of that is the members get customer support too. In maintaining Ubuntu, they get a stable Linux platform controlled by them on which software they sell can be hosted.

[QIII]

The "problem", as stated by Comcast, is that they are doing away with POP support and going to IMAP.

Canonical and Mozilla can't do anything about that.

[walts48]

The "problem", as stated by Comcast, is that they are doing away with POP support and going to IMAP.

Canonical and Mozilla can't do anything about that.

Where have they stated that, why haven't they sent out emails informing customers, and why does the mail.comcast.net server name still work with Thunderbird on Windows, and older versions of Ubuntu and other Linux operating systems?

I'll agree the Thunderbird developers (no longer paid Mozilla employees, but a separate entity) can't do anything about it.

[tomdkat]

Thanks for the replies and for the discussion. What is it about Comcast's DNS configuration for "mail.comcast.net" and "pop3.comcast.net" that seem to confuse systemd-resolved? Thunderbird aside, I can't even ping "mail.comcast.net". Is Comcast's DNS misconfigured or is this a systemd-resolved problem?

Peace...

[jerry47]

Comcast is not eliminating support for pop3. At least not in the foreseeable future. They are dropping port 110 supposedly this month. It worked the other day. Yes, I have not been able to ping mail.comcast.net or pop3.comcast.net. According to their online email support page they are moving over to pop3.comcast.net. But both of these host names get redirected to imap.ge.xfinity.com. I can ping both above host names on Windows 7. But I can't however ping either one on my iPad even though the iPad is set up with pop3 email and is working. The iPad, Ubuntu, Win7 ping imap.comcast.net without a problem. But there are no redirects. I've been in touch with comcast techs for the last two days on Twitter. There is no misconfiguration on their side. Several have responded but don't know the reason for the redirect. The only OS having an issue thus far is Ubuntu. So if November 19th is the first day the problem started then its very likely two things are contributing to the issue. One, for whatever reason, Comcast redirected the pop3 host names and Ubuntu systemd-resolved is unable to resolve the redirected names.

[jerry47]

I ran across this article about DNS issues with Systemd-resolved. Since I have a laptop running Ubuntu 18.04 as a test machine and don't care if I break it, I decided to disable systemd-resolved and replace it with unbound. The pop3 email issue is fixed. Here's the link. https://blobfolio.com/2017/05/fix-li...temd-resolved/ It proves that two things occurred. Comcast did make the redirection change on or just before November 19th and Systemd-resolved has a problem.

[walts48]

I ran across this article about DNS issues with Systemd-resolved. Since I have a laptop running Ubuntu 18.04 as a test machine and don't care if I break it, I decided to disable systemd-resolved and replace it with unbound. The pop3 email issue is fixed. Here's the link. https://blobfolio.com/2017/05/fix-li...temd-resolved/ It proves that two things occurred. Comcast did make the redirection change on or just before November 19th and Systemd-resolved has a problem.

Good to hear POP3 is working for you, and it is a systemd-resolved issue.

I switched my Thunderbird 64.0b2's on Ubuntu 18.04 and Linux Mint over to IMAP.

The 60.2.1, 60.3.1 and 65.0a1 versions are rarely used.

I'm glad we have 10 years of support for Ubutnu 18.04. Maybe the issue will be fixed in 5 years.

[tomdkat]

I ran across this article about DNS issues with Systemd-resolved. Since I have a laptop running Ubuntu 18.04 as a test machine and don't care if I break it, I decided to disable systemd-resolved and replace it with unbound. The pop3 email issue is fixed. Here's the link. https://blobfolio.com/2017/05/fix-li...temd-resolved/ It proves that two things occurred. Comcast did make the redirection change on or just before November 19th and Systemd-resolved has a problem.

Thanks for the info!

UPDATE: I just switched to Unbound and everything is working fine for me as well. Thanks again!

Peace...

[tomdkat]

I submitted a bug report on this issue:

https://bugs.launchpad.net/ubuntu/+s...d/+bug/1805027

Peace...