It makes defining generic rules simpler, in that you don't have to provide
escape-clauses for every rule. EG:
notifications:
should use <> as the reverse-path
confirmation:
must use the process mailbox as the reverse-path, to trap malformed
confirmation targets
thank-you:
may use any mailbox address in the reverse-path
I'm afraid there are at least as many exceptions to these as in the
current taxonomy. That, and your set of categories doesn't cover
all bases, and it also overlaps.
Keith