Forum der Gemeinschaft Thunderbird

AVG sends message: "We've identified a site certificate problem" "Trust for this certificate has been revoked."

Looking at certificate page that AVG provides is Greek to me. General tab displays:

"This certificate has been revoked by its certification authority"

issued to : inbound.att.net

issued by: Digicert Global G2 TLS RSA SHA256 20250 CA1

Valid from: 4/12/26 to 10/28/26

Details tab:

lists a bunch of things that I don't comprehend and offers an option to "copy to file" and lists a number of formats to copy the file to.  Have no idea which would be the one to use. 

Trying to access email directly from browser has not been successful because it wants verify my identity by sending message to my phone, but it does not send anything.

I am trying to send an S/MIME encrypted email from Thunderbird to:

jobcenter-chemnitz.netzwerkpartner@jobcenter-ge.de

The recipient certificate is provided by the official certificate directory of the German Federal Employment Agency (Bundesagentur für Arbeit).

I downloaded the recipient certificate and successfully imported it into Thunderbird under:

Settings → Privacy & Security → Certificates → Manage Certificates → People

The certificate is displayed correctly there. The email address contained in the certificate is:

jobcenter-chemnitz.netzwerkpartner@jobcenter-ge.de

The certificate is valid from July 29, 2026 to July 29, 2028 and includes E-mail Protection and Key Encipherment.

The required CA certificates are also installed:

BA-Class-1-Root-CA-4:PN BA-VPS-CA-11:PN

However, when I compose an encrypted email to this exact address, Thunderbird reports:

“You have selected to encrypt this message, but the application failed to find an encryption certificate for jobcenter-chemnitz.netzwerkpartner@jobcenter-ge.de.”

Under S/MIME → Recipient Certificates, Thunderbird also shows the certificate as “Not found”.

I have already tried:

deleting and re-importing the recipient certificate completely restarting Thunderbird after importing it manually typing the recipient address in lowercase without using autocomplete checking the complete CA certificate chain temporarily disabling OCSP

None of these changed the result.

My own personal S/MIME certificate works correctly. As a test, I can compose an encrypted email to my own email address without any certificate error. Therefore, the basic S/MIME configuration and my own certificate appear to be working.

When I reproduce the problem with the Thunderbird Error Console open, I get:

NS_ERROR_ILLEGAL_VALUE (0x80070057)

related to:

nsIMsgComposeSecure.beginCryptoEncapsulation

This seems similar to Mozilla Bug 2021265, where a manually imported recipient certificate is visible in Certificate Manager but is not found when composing an encrypted message.

Is this a known issue in Thunderbird 140 ESR, and is there a workaround for using this manually imported recipient certificate?

I can't get my e-mails today. I got a message saying The certificate for pop.centurylink.net is not valid for that server. Someone could be trying to impersonate the server and you should not continue.

Why did I get this message? I never saw this before. I like to get my e-mails. I tried reseting my router and turned off my computer and it still says the same thing. What do I do and how will I see your reply if I can't get the e-mails? Please fix this. My e-mail is toosmiley@centurylink.net

Thank you

Why do I suddenly (from one day to another) receive the message: "Das Zertifikat für imap.gmail.com stammt nicht von einer vertrauenswürdigen Quelle."

when trying to downlowd messages from Gmail?

I have not changed anything at all.

When my message filter uses the "Reply with Template" action, the reply e-mail is always PGP encrypted, even when I do not have any public key for the recipient e-mail address. As a result, the reply e-mail is always corrupted.

I am using Thunderbird 140.7.1esr on Windows 10.

I have attached a screenshot of what the reply e-mail always looks like.

In the Template that I am using, the "encrypt" button is not selected, and in the OpenPGP menu of the Template, the "Encrypt" menu item does not have a checkmark next to it.

Does anyone know how I can get Thunderbird to send reply e-mails without using encryption?

Thunderbird 140.7.0esr allows me to e-mail my OpenPGP public key to myself, but it doesn't seem to have any way for me to get access to my private key. I was wondering how to export keys? Thanks!