I posted about this earlier, except I got a message while Thunderbird was loading-

An error occurred during a connection to pop.bizmail.yahoo.com:995

Peer reports incompatible or unsupported protocol version

(Error code: ssl_error_protocol_version_alert)

I can send emails from Thunderbird, just that every time (set to download emails every 5 minutes) I get the error message window pop up. This has been like that since 9/9.

such error usually mean problems with antivirus or manual changes to force obsolete security protocols.

I tested the yahoo site. It supports TLS V1.2 and 1.3. https://www.immuniweb.com/ssl/pop.bizmail.yahoo.com/yZ6mdldJ/

Thunderbird sets it's max TLS version to V1.3 and it's minimum to 1.2 This is via hidden preferences security.tls.version.max set to 4 and security.tls.version.min set to 3

There is also a limit to how far connection renegotiatiopn can drop back security.tls.version.fallback-limit and this has been defaulted to 4 since 2019 setting a TLS version of 1.3

There is also a locking preference of security.tls.version.enable-deprecated which is set to false to prevent the max and min figures being reduced accidentally. as it also must be rue if you are going to use obsolete encryption method like SSL or TLS 1.0 or 1.1

If this were an intermittent issue I would think that Yahoo have a server in their cluster that is misconfigured, and when you get that physical server when you connect you get an error.

That this error is 100% of the time I would guess the problem is antivirus related. Of other security software like a VPN etc. Although there is nothing to suggest your setting might not have been changed in the Config Editor config editor. Check them first

Same problem for me, by now. Unable to download emails.

This morning, I can download emails again. The problem appeared, lasted 24 hours, then disappeared for no apparent reason.

A big thank you to all the people who work on TB. Great !

My emails are still not downloading to Thunderbird, even though new emails are still accessible via gmail. I do not get any error messages in TB when checking for new messages, and sending mail in TB still works fine. Turning the antivirus off makes no difference. I do remember that a day or two before emails stopped downloading, TB seemed to crash momentarily, with a blinking window, for no apparent reason, before returning to normal. May be totally unrelated, but I'm wondering if that somehow corrupted some file or something. I would rather not try uninstalling and reinstalling TB afresh just yet, if a simpler solution can be found. Any ideas?

Been away since late August with thunderbird turned off, on our return it was turned back on and now nothing is downloaded, I have tried uninstalling the antivirus (TotalAV) but thats made no difference, reinstalled Thunderbird and also tried in troubleshoot mode but nothing seems to sort it. its still downloading newsgroup messages but I just get a Mail@ servername was reset

Just an update to my message above (9/14/25 2:46pm), as of today, 18th Sept, Thunderbird has mysteriously started downloading emails again (without me doing anything), but only one at a time! So I have to keep clicking the 'get messages' button to get each new message, even though there are many new messages waiting on the gmail server. Sending mail is still fine, and I never get any error messages. Any help most appreciated.