In message

..net, at 18:31:58 on Wed, 17 Apr 2013, Neil Williams
remarked:
I'm not so sure. When the postman delivers a whole bag of mail to a large
user, don't you think he just crosses off all the "Recorded" items that
are believed to be enclosed, without individually correlating them. At
that point all the post is the same to the recipient, and indeed most
post-rooms will dispose of all the envelopes and lose the very fact it
was sent "signed for".

I doubt it, as the signature must be recorded.

The signature is recorded by the postman, in a little book. The
recipient records nothing.

Large post rooms then dump all the letters into a letter-opening machine
and discard the envelopes. Smaller post rooms do the same by hand.
--
Roland Perry