mail/rmail-spam-filter.el: It seems (?) to work.
At a few places, it leaves the raw mbox buffer visible, either while
it displays a prompt or waits. This is poor, but it does not seem
-straightforward to show a message at that poiny without messing up
+straightforward to show a message at that point without messing up the
rest of get-new-mail. (See rmail-get-new-mail-filter-spam, end of
rmail-get-new-mail-1, and end of rmail-spam-filter for FIXMEs.)