Forgive me for intruding, this thread got me curious

When you say "whitelisted email address", exactly what program, component, or setting are you talking about? I can't seem to find any whitelist setting in Avast Mail Shield template that matches what you are discussing for endpoint protection.
If you are talking about a whitelist on a Mail Client (ie endpoint), then it is likely you are talking about a junk/spam whitelist which determines an action on how to handle spam. I am sure that would still be scanned by the Mail Shield.
Of course if you are talking about Premimum with Exchange Server mailbox protection, thats something I don't have so can't comment on that
