I have been told to not use SSL scanning on my BD IS 2018.
However, are my Thunderbird emails & my wife's Outlook emails being scanned by BitDefender if SSL is turned off. Thank you.
This depends on how the email client is setup. If it downloads the emails on your computer through SSL, then the option would need to be enabled yes. Bitdefender could still scan the emails during a system scan, or if you tried to do anything else with the attachments (save them somewhere on your computer - outside the mail file, run them etc).