Lovely stuff. Three suggestions.
1. The previous extension named confused me. The new ones are much
better. But the document title could be updated to match.
Good idea. Changed.
2. IMHO dsn-redirect should apply to the vacation and notify/mailto
commands as well as to redirect.
Alexey pointed out that this really doesn't apply to vacation. As for notify,
perhaps that should just be done in the base notify-mailto specification since
it isn't done yet.
3. An ORCPT example in the paragraph about ORCPT, something like
"rfc822;midas(_at_)example(_dot_)com".
Good idea as well. Added.
Ned