[Mailman-Users] Add PayPal to DNs publishing DMARC p=reject

[Stephen J. Turnbull]

Peter Shute writes:

 > Thanks, I understand now. If the result of this is that replies go
 > to everyone on the list, this is something we don't want for our
 > list. Private replies becoming public means trouble, and we have
 > enough of it already when people Reply All by accident.

In that case, in Mailman 2.1.18-1, you probably get the best of all
worlds by setting

    'from_is_list' to 'Munge From'

which puts the list in "From", deleting any other addresses from
"From" (thus disabling DMARC), and then puts the poster in "Reply-To",

    'reply_to_list' to 'Poster'

which leaves the "Reply-To" header as it finds it.  Finally, set

    'personalize' to 'Full Personalization'

which puts the recipient in "To".  The first two are on the General
Options page, the last on the Nondigest Options page.

The rules for these options are complicated, but if I've thought
correctly about this, in most cases the header of the post as
distributed to subscribers will say

    To: each-subscriber at home
    From: the-list at your-org
    Reply-To: the-poster at home

Although "the-list" is *visible* in "From", conforming mail clients
will *not* pay attention to it (the "rules" say Reply-To takes
precedence over From as the author's address), and even a Reply All
will produce a message addressed as

    To: the-poster at home
    From: each-subscriber at home

In order to also CC the list, the replying subscriber would have to
deliberately copy/paste the list address into "To", "Cc", or "Bcc".
This depends on the replying subscriber's mail program, so there are
no guarantees, but it seems very unlikely to me that any of your
subscribers will inadvertantly CC the list with that configuration.

The only downsides are that (1) the list appears to claims to be
authoring all the posts, and send each privately to each subscriber
(but I wouldn't be surprised if few subscribers notice more than
"something changed") and (2) full personalization uses more resources,
potentially a lot more.  On the other hand, with reasonably modern
equipment and say 5 lists each with 500 subscribers and 10 posts each
per day, the server will literally spend more time waiting for the
next post than it does delivering them.

Network bandwidth is a more important consideration, because if you
have many subscribers at one domain, you can tell that domain to
deliver to a long list of those subscribers, and then send the message
once.  But if you personalize, then each message is (slightly)
different, and must be sent separately.  If you want advice about
resource usage in your situation, don't hesitate to ask here.  I have
no experience with that configuration, but I suspect Mark has the
numbers on tap, and I'm sure many of our lurkers do.

Hope this helps,

Steve