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.
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.
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 ?
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.”
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.
Thanks for the update and clarification.