I’ve disabled Avast Mail Shield because it’s intrusion into Outlook (Office 365 desktop installation) TLS communication with Gmail mail servers. (I have a screenshot, but I don’t see how to embed an image here).
"Internet Security Warning
The server you are connecting to is using a security certificate that cannot be verified.
A certificate chain processed, but terminated in a root certificate which is not trusted by the trust provider."
View certificate:
Issuer: Avast Web/Mail Shield Root, A…
Subject: imap.gmail.com
OU = generated by Avast Antivirus for SSL/TLS scanning
Obviously, generated wrong.