David wrote:

Thanks Brian - that helps but you still have to do all the views or
at least the ones that can be changed, then in each view you change
the font size in "Other Settings" and "Automatic" for each one.

Since the Message view is the default view for all mail folders (except
Outbox and Sent Items), using /cleanviews, then modifying the Message view
will change ALL mail folders at one time.
--
Brian Tillman