After reading through various threads on this topic, I called Avast technical support and they were very helpful.
What I wanted to do was simply KEEP my SSL function in my MAC mail preferences checked because my web host tech support told me that they not only encrypt but also scan for viruses etc. and, besides, I am paying them extra for SSL functionality.
Therefore, all I wanted to do was disable the warnings and alerts from the Avast program. In Avast preferences-->PopUps, I turned off "Warnings" and "Alerts." The rep told me that Avast will continue to scan my iCloud mail and will warn me about any serious problems while my web site host email account will be taken care of on their server. I should not receive the annoying SSL alerts anymore.
The Avast rep was clear and very helpful.
Now we'll have to see if the alerts to away and I never get any viruses!