Scanning things that come into my computer is cool. I'm okay with that.
This includes my email. Scanning my email, I'm okay with.
And I know you can't scan my email before delivering it to the mail client if I use SSL. I understand that. I'm also okay with that. That's why I told you to stop asking me about the IMAPS connections and just ignore them.
And after an update, suddenly, without asking, man-in-the-middle-ing my SSL connections, causing Thunderbird to start screaming about how all the mail servers have lying SSL certificates?
That's not cool. I'm not okay with that. You need to present that kind of thing as an OPTION. You can default it to "on". You can even put "(highly recommended)" next to it if you like - but that damn well needs to be something that I know about BEFORE Thunderbird reports that someone is impersonating my mail servers, because that shit is a sign of something Seriously Wrong With The Internet and I should NOT have to dig up the lying certificate to realise that you did it.
And now I've just turned the mail scanner off completely, because seriously, fuck that.
Not cool, Avast. Not cool.