Thank you, Stephen. Your suggestions were helpful, and I genuinely appreciate
the time and effort you took to provide insights.
However, after careful consideration, I realised that implementing the
technical suggestions might be beyond my current capabilities. I'm now
exploring migrating to a hosted service to manage the list.
Transforming to a hosted service would alleviate the technical burden and
ensure the smooth operation of the list. If anyone has recommendations or
experiences with reliable and affordable hosted services for Mailman list
management, I would greatly appreciate your insights and guidance.
Additionally, if there are specific features or considerations I should
consider when evaluating hosted services, please feel free to share your
thoughts.
Once again, thank you for your assistance and support.
With regards, Francis
________________________________
From: Stephen J. Turnbull <turnbull.stephen...@u.tsukuba.ac.jp>
Sent: 07 February 2024 13:20
To: Francis Jayakanth <fran...@iisc.ac.in>
Cc: mailman-users@python.org <mailman-users@python.org>
Subject: [Mailman-Users] Non-delivery of approved messages
External Email
Francis Jayakanth via Mailman-Users writes:
> The list is running on Mailman 2.1.26.
If possible you should upgrade Mailman, currently at version 2.1.39.
Almost all of the releases since 2.1.26 are primarily oriented to
"security" and "reliability" issues. I don't recally any offhand that
would help alleviate your current problem, but who knows? And the
changes address genuine vulnerabilities that have been exploited at
many sites in the past.
> During the last couple of weeks, approved messages are not being
> delivered to the list members. When I check the Email &
> collaboration alerts in the Microsoft 365 Admin Portal, I see the
> following message:
Do you mean that Microsoft provides the email services to your
organization or to a host that your organization uses, and they're not
letting *your* traffic go out to *anyone*? That's a new one to me.
"Shocked but not surprised", as the saying goes.
Your problem is with Microsoft. You need to get their help,
especially if they are providing your email services. They do not
tell us why they block some messages or some users rather than others,
and it often seems completely random. Here it sounds like the
"suspicious activity" is sending lots of mail to many addresses. Ie,
you're being throttled *because* you're running a mailing list. But
you'll have to negotiate with them if that's what's happening.
The generic recommendations are
1. Get your users off Google, Yahoo, Verizon, and Office365. Yeah, I
know that's "impossible", but it's the single most effective
method for improving the experience of mailing list subscribers.
2. If you manage your own mail system, make sure your DNS records for
SPF and DKIM are in order, and that your MTA is configured to sign
messages properly. If somebody else is responsible for that, ask
them to check and fix any problems. (This applies to 3 throuhg 7
below, too.)
3. Implement DMARC on your system. This doesn't have a standards-
based effect on posters whose email accounts are not on your host,
but it may enhance your site's general reputation.
4. Implement the ARC (Authenticated Received Chain) protocol. The
basic idea is that any change your mailing list makes such as
adding list tags to the Subject or an organizational footer to the
body of the mail will break the DKIM signature that attests that a
valid user on the original sending system (the author or "From"
address) sent the mail. ARC allows you to say (in a way that some
email software understands) "We validated this message, the
signatures were in order, and if it turns out to be spam or
whatever you can blame us. Here's our signature so you can
believe it." I don't know offhand if Microsoft implements it or
if they put much weight on it, but it can't hurt. Google and
Yahoo do put a fair amount of trust in it, I'm told.
The following advice is generally good, but it may not be influencing
your current problem.
5. Put spam filters on your *outgoing* mail. Folks are of two minds
about this (if you're primarily a mailing list site and you filter
incoming, you won't catch anything new going out), but sometimes
you can catch things going out that you wouldn't catch coming in.
This is especially true if you use Bayesian or "machine
learning"-based spam filters so you can use experience to tell
them in the context of the mailing list whether it's spam or not.
6. Check your moderation queues ("held messages") for unusual amounts
of spam -- some of it may be getting through to your subscribers.
7. Check the subscription queues ("awaiting address confirmation")
for an unusual number or a pattern of particular addresses being
subscribed to a large number of unrelated lists. Unfortunately,
the confirmation process can be abused by malicious third parties
to send large numbers of address confirmation notices to unrelated
addresses, thus clogging their mailboxes. Not only is this
annoying and even a denial of service to the victims, but it also
can hurt your site's reputation.
I'm sorry I can't be of more help, but the large providers are far
more sensitive to any spam that gets through than they are to lost
mail, because they can blame lost mail on the sender, while users
hold them responsible for spam.
Regards,
Steve
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