[MlMt] Review muted items

[John Cooper]

Bill Cole wrote (at 8:11 on 31 Jan 2019):

> A message is muted if it is a thread descendant of a muted 
> message....if you delete all members of a muted thread, future replies 
> in the thread are not muted.

That hasn't been my experience. I've occasionally muted high-volume 
contributors to the MailMate Users group, and new threads by those 
contributors are muted until I select one and unmute it.