The attached patch fixes it.
--- smail-3.2.0.115/debian/rules 2006-03-14 15:08:06.000000000 +0100 +++ smail-3.2.0.115.new/debian/rules 2006-03-14 14:58:17.000000000 +0100 @@ -58,8 +58,7 @@ rm -f debian/arch-test conf/EDITME for f in `find . -name AUX-support -prune -false -o -name Makefile` ; do \ - perl -i.dep~ -ne 'print || die $$! \ - if 1 .. /^# DO NOT REMOVE THIS LINE/' \ + perl -i.dep~ -ne 'print || die $$! if 1 .. /^# DO NOT REMOVE THIS LINE/' \ $$f ; \ done