[Discuss] Thunderbird not connecting to Comcast IMAP server

[epp at vivaldi.net]

This appears to be an IPv6 issue on this system, since TB otherwise 
works fine on the other system.

I used TB's Config Editor and toggled the entry for 
network.dns.disableIPV6 from "false" to "true". Relaunched TB and it 
worked. Toggled it back to "false" and TB again fails to connect to Comcast.

So the question now, is: What changed on /this/ system that is 
apparently now preventing Thunderbird (and Evolution) from connecting 
via IPv6 and how to correct it?

There is another entry in the config that is supposed to flip the 
protocol to IPv4 (network.http.fast-fallback-to-IPv4), if there is no 
response via IPv6 within a short amount of time and that entry is set to 
"true".


On 10/9/19 9:16 AM, epp at vivaldi.net wrote:
> Both Fedora 30, with the same packages.
>
> -----Original Message-----
> From: Derek Atkins <derek at ihtfp.com>
> To: epp at vivaldi.net
> Cc: discuss at blu.org
> Sent: Wed, 09 Oct 2019 8:59 AM
> Subject: Re: [Discuss] Thunderbird not connecting to Comcast IMAP server
>
> Are both systems Fedora 30 with the same sets up upgrade packages?
> -derek
>
> On Wed, October 9, 2019 8:52 am, epp at vivaldi.net wrote:
>> Nothing changed on this end.
>>
>> It connected fine up until Sunday night. But I can't explain why TB
>> successfully connects to Comcast on one system, but not on the other.
>>
>>
>> -----Original Message-----
>> From: Derek Atkins <derek at ihtfp.com>
>> To: epp at vivaldi.net
>> Cc: discuss at blu.org
>> Sent: Wed, 09 Oct 2019 8:32 AM
>> Subject: Re: [Discuss] Thunderbird not connecting to Comcast IMAP server
>>
>> Did anything change on your end?  Did you take any updates?
>>
>> Could it be a TLS ciphersuite incompatibility issue?
>> I believe that F30 disabled a BUNCH of old ciphers.
>> If Comcast is running an older IMAP service you might not have compatible
>> ciphers anymore.
>>
>> -derek
>>
>>
>> On Wed, October 9, 2019 8:27 am, epp at vivaldi.net wrote:
>>> Beginning this past Monday, Thunderbird and the SeaMonkey suite (on
>>> Fedora
>>> 30) mysteriously stopped connecting to Comcast's IMAP mail server.
>>>
>>> In trying to diagnose the issue, I also installed Evolution, which also
>>> failed to connect.
>>>
>>> After removing the Comcast accounts from Thunderbird, attempts were made
>>> to add them back in, however when Thunderbird attempted to check the
>>> password, that process becomes stuck, as if Thunderbird cannot resolve
>>> the
>>> IP address(es) for the Comcast server. I let it sit like that for 15
>>> minutes without success, then clicked Cancel.
>>>
>>> Thunderbird otherwise connects to non-Comcast IMAP servers perfectly.
>>>
>>> I also have Geary installed and that successfully connected to the
>>> Comcast
>>> server, yet the other three email clients could not.
>>>
>>> Could this be an issue on Comcast's end? If it were a DNS or resolver
>>> issue, then nothing would connect.
>>>
>>> I have Thunderbird installed on a second system and it connected to
>>> Comcast successfully on that, last night.
>>>
>>> Thanks for any replies/suggestions.
>>> _______________________________________________
>>> Discuss mailing list
>>> Discuss at blu.org
>>> http://lists.blu.org/mailman/listinfo/discuss
>>>
>>
>> --
>>         Derek Atkins                 617-623-3745
>>         derek at ihtfp.com             www.ihtfp.com
>>         Computer and Internet Security Consultant
>>
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>