Thunderbird Secure connection failed

[Rainbow1112]

Using thunderbird 52.3.0

Unable to send/receive emails due to Secure connection failed.

[tanstaafl]

Please resize the image so that it fits on a normal screen.

Occasionally there are temporary problems with Thunderbird connecting to a Mozilla web site due to
a bad certificate etc. Usually when that happens it only effects some users. When the problem occurs
it effects the contents of the optional startup page, the help text etc. and anything else that requires it
fetch data from the web site. However, it should have no effect on your ability to get, read, write or
send mail.

None of your accounts should be making a secure connection to the Mozilla web site. They make
secure connections to your email providers mail servers instead. Did you try to check for new mail
or did you just assume it would fail? If it failed, what is the complete text of the error message?

See if you can go to https://start.thunderbird.net/en-US/release/ using a browser. Its possible your
problem is not limited to Thunderbird.

[Rainbow1112]

I'm using kaspersky free antivirus

I added Kaspersky ssl key to thunderbird and the error disappear.

however i still cant send/receive email. it show connected to outlook.office365.com but no email is downloaded.

[DanRaisch]

What settings do you have for that account for:

Port number?
Connection Security?
Authentication Method?
Are you entering the full email address as user name or just the bit before the @ symbol?

[tanstaafl]

See http://kb.mozillazine.org/Hotmail if you're using outlook.com . Sometimes people use the outlook.office365.com server when using it. See
https://support.mozilla.org/en-US/questions/1059850 if you're really using Office365 as your email provider

[Rainbow1112]

I'm using hotmail/outlook

on further troubleshooting when i disable kaspersky free i'm able to retrieve email. somehow kaspersky is blocking the connection but i have already added the kaserpsky ssl cerf to thunderbird..

any work around?

[tanstaafl]

Does Thunderbird support the CA used by the Kaspersky SSL certificate? If not, the SSL certificate is ignored as invalid.

Do you have a similar problem when using Firefox with webmail? if so see https://support.kaspersky.com/general/error/13585

https://security.stackexchange.com/ques ... google-com talks about
"My understanding is that Chrome, Edge, and IE use the built-in Windows certificate store, and that Firefox does not". I'd
expect Thunderbird to do the same thing as Firefox.

It sounds like Kaspersky wants to root your certificates just like Avast does, in order to scan data sent over a secure connection.