avast 20.7.2425: issue with Thunderbird 78.2.2

[jmadec]

When the Mail Shield is enabled in the latest version of free avast, it is impossible to send or receive mails with Thunderbird 78.2.2. When I try to send a message, I get the following error message:
"Peer’s certificate has an invalid signature."

If I disable Mail Shield, everything works fine.

[DavidR]

My default email is thunderbird and is version 78.2.2 also and I'm not experiencing this.  However, I'm basically using POP (port 995) & SMTP (port 465) and secure settings SSL/TLS for both.

You don't say if this is IMAP that you are using, I don't use that so I can't comment.

[jmadec]

I'm also using POP and SMTP with the default ports (995 & 465) and SSL/TLS for both.

Maybe this issue is related to a similar one encountered by AVG users. See https://support.avg.com/answers?id=9060N000000ggs1QAA

[DavidR]

I'm also using POP and SMTP with the default ports (995 & 465) and SSL/TLS for both.

Maybe this issue is related to a similar one encountered by AVG users. See https://support.avg.com/answers?id=9060N000000ggs1QAA

Well since AVG is a part of Avast Software that is a possibility.

Have you tried export the Avast Certificate and then Import it into Thunderbird, it should be the same steps in Avast (and geek:area) in Avast to export the certificate ?

[jmadec]

I've followed your suggestion but the issue is still there after importing the avast mail shield certificate.

Furthermore, when importing this certificate in Thunderbird, I get the following message:
"This certificate is already installed as a certificate authority."

[jmadec]

Issue solved

Apparently, as explained by the AVG user in the link I've posted previously, one Trust option was unchecked
 for the first Avast Web/Mail Shield  -> Avast Web/Mail Shield Root certificate. This option is "This certificate can identify websites". After checking it, everything works as expected again.

[DavidR]

Thanks for the update and clarification.