In 5c85f09 I began the process of running messages through wpautop() by default.

I want to make that conditional based on a filter return value. Leaning towards defaulting to not applies, to prevent breaking those who may already have happily working messages. However, want a 1 line add_filter( 'some-filter', '__return_true' ) or vice versa solution to running things through.

Also, provide extra parameters of the current message type, eg pending, approved, denied, admin pending, etc, as well as the user ID being acted on at the time.