This warns you that C<"fred@example.com"> is going to turn into
C<fred.com> if you don't backslash the C<@>.
-See http://www.plover.com/~mjd/perl/at-error.html for more details
+See http://perl.plover.com/at-error.html for more details
about the history here.
=head2 @- and @+ provide starting/ending offsets of regex submatches