an example of "double send" mitigation in practice

On Mon, Jun 1, 2015 at 8:30 AM, David Nicol <davidnicol@gmail.com> wrote:

>
>
> And yes, double-sent e-mail is a problem, but it is a mild one, and how a
> MUA (or listserv software) deals with receiving the same message both
> directly and from a mailing list (as this message will be delivered, to
> four recipients who are on the mailing list it is also sent to) is a user
> experience design choice, as there isn't that much riding on it. For
> instance, listserv software might not bother to deliver to a recipient
> listed in the message headers, I think that's a fair optimization listserv
> software may do.
>

Found it! I knew I'd seen that option somewhere and it is in subscription
settings with GNU Mailman. Here's the relevant section from the GNU Mailman
subscriber manual, which is organized as a FAQ list. So as I was
saying, *e-mail
does have a situation analogous to double-spend*, complete with implemented
mitigation measures. To give paranoids something else to worry about, *this
feature makes it possible for a capable and sneaky message originator to
select mailing list members who have the feature enabled for exclusion from
distribution of a message*, as listservs have no mechanism available for
verifying that listing as a To: or Cc: recipient genuinely represents that
the message was in fact served directly to the alleged recipients.

7.2 How can I avoid getting duplicate messages? (duplicates option)

   Mailman can't completely stop you from getting duplicate messages, but
   it can help. One common reason people get multiple copies of a mail is
   that the sender has used a "group reply" function to send mail to both
   the list and some number of individuals. If you want to avoid getting
   these messages, Mailman can be set to check and see if you are in the
   To: or CC: lines of the message. If your address appears there, then
   Mailman can be told not to deliver another copy to you.