This C/R idea is used in other forms in other places. These C/R systems
get similarly abused by spam-bots and worms that feed them reams of
email addresses that result in everyone else getting the confirmation
messages ("backscatter"). The problem is that Joe often doesn't want C/R
messages in his mailbox and will sometimes report them to entities like
SpamCop or his favorite DNSBL, particularly if these C/R messages get
sent to a spam trap address. This is also the reason why many
Listserv(tm) managers edit the response templates with .QQ directives so
as to keep Listserv from being so talkative.



>>> "A.Omer Koker" <[log in to unmask]> 9/13/2006 4:37 PM >>>
3-sends back a mail message TO Joe#box asking him to confirm his
existence
by clicking on a web link

4a- if Joe clicks on the special link the app then goes on to deliver
(to
listserv) the original message Joe sent as well as add Joe to a
whitelist.
This way the next time Joe@box sends an email to ANY list/user on your
domain his mail gets delivered directly to listserv.
  
4b- however if Joe does not click on the link because of a forged
header,no
such user, whatever then his  original mail does not get pushed on to
the
listserv but dumped.  In the case he did not click because he missed
the
message from the app, next mail from Joe@box will be asked to confirm
as
well.