Thunderbird Community Forum

Hi there.

I'm in Alberta, where we have recently changed timezones. Note that the CLOCK has not changed yet, as we are still before the date in November when we would "fall back". We were UTC-6 summer and UTC-7 winter. Windows called this "Mountain Time (USA and Canada), but now the "Mountain Time (Alberta)" timezone is in Windows after the 2026-09 Preview Update (KB5124010) (26300.9550).

When connecting to Shaw.ca's IMAP servers, the certificates that were valid prior to the Windows update are now reported as invalid. This has been confirmed across two separate PCs with different email accounts. The data for the certificate LOOKS valid (see screenshot) and is the same before and after the timezone change.

The failure occurred on the latest ESR release of Thunderbird, as well as 156.0 and 157.0 non-ESR.

Thanks :)

We are not getting emails because we keep getting an error message which reads The certificate for imap.shaw.ca does not come from a trusted source.

I can't find the certificate in order to delete/distrust it. Its name is my mail server. Organization: Lumen Technologies, Monroe, Louisiana

Subject Name Country US State/ProvinceLouisiana LocalityMonroe Organization Common Name Lumen Technologies, Inc. mail.centurylink.net Issuer Name Country Organization Common Name US DigiCert Inc DigiCert Global G2 TLS RSA SHA256 2020 CA1 Validity Not BeforeWed, 27 Aug 2025 00:00:00 GMT Not AfterSun, 27 Sep 2026 23:59:59 GMT

In Plain English how to use and secure encryption on all outgoing emails please and whether or not to use this great advantage. Many thanks to all those who contribute to this work, PB

https not recognized by Firefox in 151 Thunderbird on silicon iMac with Sonoma. Tried & checked many solutions with no results.

Firefox browser primary , always Nothing in Modified Important Preferences With Extensions off still a problem

Mozilla suddenly says "The certificate for mobile.charter.net does not come from a trusted source." It will not let me get my emails. Is this a problem with Thunderbird or Charter (Spectrum) I am able to receive email on my I Phone. I do not know which Thunderbird version and can't find it using your instructions. Help please

When i try to update my schooles secure mail, i get the nev certifikat and the Root, and Ca1 under autoreties and give it the right rights but it keeps giving me this error message " Certificate verification failed with the following error: The peer's certificate issuer is unknown. (Error code: SEC_ERROR_UNKNOWN_ISSUER)"

I am using Thunderbird 151.0.1 (64-bit), and I get the "trusted source" message in a pop-up every time Thunderbird checks for email. There is only an option to Dismiss presented. My account name changes color to red and has a red triangle with an exclamation mark displayed. I went to Settings > Privacy & Security > Security > Certificates > Manage Certificates and looked at all the certificates listed in the Certificate Manager > Authorities (which is the only section with anything listed) and don't see anything from mobile.charter.net. I can go to SPECTRUM.NET (Charter) and view my email with no problems. I'm at a loss as to be able to view my email in Thunderbird.

Receiving emails was no problem, but when sending one I was repeatedly asked for my password. I did check the save password in the dialog box. I checked the account settings and saw a yellow alert next to certificate exception and clicked on remove. That apparently was a mistake because now I can't get into email since the security certificate is not valid. Reinstalling Thunderbird may be needed, but I need some advice before I try anything else.

I've been trying to set up a GPG key, but Thunderbird doesn't recognize my pub.asc file. So I created a PGP key thru Thunderbird and I would like to export it as ASCII-armored public key.