Log Message:
Initial import of qconfirm, an implementation of a delivery confirmation
process for a mailing list or mail address. It is invoked by qmail-local
through a dot-qmail file, and can reduce the amount of junk mail hitting
a mailbox or the mailboxes of mailing list subscribers. qconfirm
performs this delivery confirmation process either sender based or
message based.

When used for a public mail address, not a mailing list, qconfirm is
capable of detecting follow-ups on mail messages originated from this
mail address, and doesn't request delivery confirmation is this case.
qconfirm also is able to identify delivery confirmation requests from
recipients of mail messages, and automatically confirms the delivery
if desired.