[Mailman-Users] mm-handler same as postfix-to-mailman.py

[Dmitri Maziuk]

On Sun, 6 Jan 2019 15:47:01 -0700
Grant Taylor via Mailman-Users <mailman-users at python.org> wrote:

> Hi Jim,
> 
> On 1/4/19 3:40 AM, Jim Ziobro wrote:
> > Setting up mailing lists in a separate domain has a nice
> > administrative appeal.

We used to run irix whose sendmail sent every message from host.domain
and every A record had to have an adjacent MX record for e-mail to even
work. That way lies madness.

> > I did a little more research to see how popular that method might
> > be. I got a list of 1922 US universities and 457 have a host
> > "lists...." and 191 have a host "list..." in their DNS.  I surveyed
> > a few and ran across: Mailman, Lyris, Sympa, Listserv, Majordomo,
> > and Google groups. Many universities outsource their Email to
> > Outlook which has it own Group capability.

Our university has lyris @ lists.uw, googlegoups, and has recently
bought into lookout'365! as well. While we run our own mailman
instances.

We have "lists" in our little niche. It's the web front-end, our list
traffic comes from @domain. 

So 500 out of 2000 universities having "list(s)" in DNS doesn't really
mean all that much.

> I think it should be somewhat easy to test the SMTP envelope sender
> to see if it's subscribed to a list that is the SMTP envelope
> recipient. If the sender is not a subscriber the MTA can reject the
> message.

Rather trivial with postfix but a) we have bona fide subscribers
posting rom their gmail instead of subscribed From: -- I want those to
get moderated instead of bounced, b) it is of course subject to
spoofing, and c) how much of a problem is it IRL?

In our -- admittedly very lightly loaded -- domains, it's RBL and
fail2ban that seem to provide best bang for the buck.

-- 
Dmitri Maziuk <dmaziuk at bmrb.wisc.edu>