without knowing the sever name I can suggest exactly nothing. I would assume the server administrator has not kept up with the time and is using obsolete security. But without a server name that is pure speculation. It might just as well be you anti virus making a mess of things.

It happened with all sorts of servers. I should have pointed out this.

The problem has been solved by going back to V52.9.1. I am unable to use newer official versions. The latest official version that I can start is V52.9.1. I tried version 6.0.1, and got this problem. It looks like that I will have to live with V52.9.1 for the foreseeable future.

A quick search on the error code produces plenty of suggestions for Firefox, which in this case can be applied to TB:

https://support.mozilla.org/en-US/questions/1214366

https://support.mozilla.org/en-US/questions/1153050

Config. editor is under Tools/Options/Advanced/General.

hongz said

It happened with all sorts of servers. I should have pointed out this. The problem has been solved by going back to V52.9.1. I am unable to use newer official versions. The latest official version that I can start is V52.9.1. I tried version 6.0.1, and got this problem. It looks like that I will have to live with V52.9.1 for the foreseeable future.

You still have provided exactly zero useful information as to the cause.

Even the stuff SFhowes is linking to describes broken security on mail/web servers and workarounds to make the programs continue to function with broken security. If you are dealing with a server that is not secure, perhaps you would actually like to know that. Before it results in a virus being attached to your outgoing mail. That way you might be able to seek improved security from your provider.

So I reiterate my previous questions. What servers?

This error shows up for messages that I receive regularly. It never happened before I ventured into 6.0.1, and has never happened since I got rid of it. For example, one server is www.zazzle.com:443. All servers are from well known companies. I have created a massive set of spam filters, so the messages with embedded links that I view are from institutions such as Boston Globe, Audubon, Carter Center, Habitat for Humanity, TripAdvisor...

hongz said

This error shows up for messages that I receive regularly.

So you see this error message when you display the messages, not when you get the mail. Is that correct?

It never happened before I ventured into 6.0.1, and has never happened since I got rid of it.

The security landscape is a fairly fast moving target. cyphers which the message appear to be about are deprecated all the time when some mathematical genius publishes a way to decrypt them. Going back a version just installs a version with what is considered to be broken security. It is not and never should be considered a "fix" it is at best a very temporary workaround.

For example, one server is www.zazzle.com:443. All servers are from well known companies.

lets look at this. WWW server names are for the world wide web (WWW) which these days is just called the web. I would expect requests to a www server to be HTTP or HTTPS requests on ports 80 (unencrypted) or 443 (Encrypted)

So I take this server name and port and put it into Firefox and in the web console of Firefox I see all sorts of error related to cookie sniffing by zazzle of Google double click face book and a number of others because Firefox has tracking cookies disabled. So it might be unscrupulous business practices form part of this answer.

However when I create an email with a link to ww.zazzle.com:443 it does work. So I think we need to look somewhere else for the lack of ciphers. Can you open the link in Firefox? Firefox and Thunderbird share code in this area, so any error message in Firefox might be illuminating. Even the lack of it.

I have created a massive set of spam filters, so the messages with embedded links that I view are from institutions such as Boston Globe, Audubon, Carter Center, Habitat for Humanity, TripAdvisor...

I do not know that is all that relevant, but I will say manually created and managed spam filter are never going to do more that cause you long term pain and keep you busy. They do provide short term satisfaction, but they do not work long term, which is why you have a "massive set"

Yes, I should have mentioned that the error happens only when I view an email. It may happen multiple times for one email probably depending on the number of linked images.

I am unable to use newer official versions. (sorry for the wrong link in my previous post).

Could offer a suggestion for the filtering out spams of which I get dozens every day (over 100 sometimes). My filters have filtered out them almost 100% so far, but I still need to add new ones periodically.

hongz said

Could offer a suggestion for the filtering out spams of which I get dozens every day (over 100 sometimes). My filters have filtered out them almost 100% so far, but I still need to add new ones periodically.

Make sure the filters actually mark the mail as spam. It is common to just delete them, but that does nothing to educate the build in spam filter. After a few years I rarely see spam in my inbox and the Thunderbird spam filter is it. I use nothing else.

hongz said

Yes, I should have mentioned that the error happens only when I view an email. It may happen multiple times for one email probably depending on the number of linked images.

I think your anti virus might well be the problem child in this. No one else has an issue is what makes me think it is so. What anti virus are you using?

You did not answer about what happens when you click on this link. www.zazzle.com:443 Sure you get an error in Thunderbird, what do you get when you click the link here in the forum.

Another user recently had a similar problem with their security program, Kaspersky Total Security, not allowing TB add-ons to update due to 'certificate errors'. The solution was to add an exception in KTS, but here it may be sufficient to stop the security program from scanning SSL connections, or the equivalent, if it has that option. I don't think the picture in the original post even comes from TB. If I open https://www.zazzle.com:443 , it opens correctly with no errors.

All my spam filters move the email to folder "Spam".

I can open "https://www.zazzle.com/" or "www.zazzle.com:443" without any problem. They show the same page.

sfhowes, I no longer have the problem after going back to 52.9.1.

I understand there's no problem with 52, but it would still help to know what is your security/AV program and its options for SSL connections and email scanning. That program may be compatible with 52 but not with 60.

Thank you for the clarification. I have just realized that I totally fooled myself. I was looking at download archive: https://archive.mozilla.org/pub/thunderbird/releases/

Noticed directory 6.0.1 is after 52, and assumed it was newer, so tried it. Actually, it is much older than 52. The only official one newer than 52 is the current 60.

I will try the latest build once every few months to see it will start working on my computer.

I forgot to say that I use Windows Defender. Do not use any third-party anti-virus software.

I think it's fair to suggest your issues were caused by using TB 6 from 2015.

sfhowes said

I think it's fair to suggest your issues were caused by using TB 6 from 2015.

Yes, it all makes sense now considering how old TB 6 is. Lesson learned. This probably will happen again in the future if I am unable to use any version older than 52.