[Mailman-Users] list mail increasingly flagged as spam

[Mark Sapiro]

On 12/19/2016 04:52 AM, Glen Page wrote:
> I have recently begun to see (and get complaints from some of my users) our list messages being flagged on many users end as spam messages. Wondering if there is anything that i can do on our end to decrease the likelyhood of our messages being flagged as spam. If it would help, I can send some header info from some of our messages.


See the article at <https://wiki.list.org/x/4030690>

Even before doing any of the things there, do all of the following.

1) Ensure your sending server has full circle DNS
<https://en.wikipedia.org/wiki/Forward-confirmed_reverse_DNS>. I.e. the
domain the server identifies itself as in HELO/EHLO has an A record with
the IP address of the server and rDNS lookup of that address points back
to the domain.

2) Publish SPF for the list domain authorizing the sending server.

3) DKIM sign outgoing list mail with the list domain.

These are not guarantees but they are all things that if not done make
your mail look less legitimate to at least some recipients.

Also if you are not applying DMARC mitigations to your list mail, this
can be a problem, particularly is the "spam" is mail sent From: users in
domains publishing DMARC p=quarantine. See
<https://wiki.list.org/x/17891458>.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan