A software security suite probably shouldn’t tell the user to turn off e-mail encryption so as to better be able to scan for viruses. That seems fairly daft.
I’d suggest that if Avast would like to ensure e-mail security, that providing an outbound smtp server might be a better idea?
If you want avast to scan the mail, you have to turn off the SSL in the mail client and let avast do the SSL
So the SSL connection is still there just moved to avast
I rather doubt that is going to happen with over 100million avast users.
It also wouldn’t get round having to create the account in your email client and also not to select SSL so that avast can scan the email content and then initiate the StartTLS connection.