If comment is added to a Service Desk request via email, allow admins to override default behaviour and set comments to Internal or Public whenever possible.
if email sender is Customer or Participant or Agent or the Reporter, the comment will be public
Otherwise the comment will be internal.
New options as default comment visibility:
Default: same as above
Public: make all comments public regardless who sends the email. This will be a kind of violation of the rule that Collaborators cannot respond to customers.
Internal: make all comments Internal, unless Customer or Participants respond, in these cases, Public comments will be added.