Hi Steve,
Somebody (maybe me) forgot to send this to the list. Since you mention Mark, I'm sure "to list" was your intention, and I'm going to quote in full as well.
Steve Brown writes:
Thanks, other Steve. I know so little about Alter Messages and DMARC mitigations that I basically left all those settings at their defaults unless I was advised otherwise by the MM3 hosting service (Mailmanlists.net out of Australia).
Internet mail is very complicated. I am somewhat familiar with at least 50 documents describing how it's supposed to work (sometimes multiple editions of the same one!), and I discover new ones that I really ought to learn about several times a year.
First strip Reply-To: nothing; neither Yes nor No is checked
Pretty sure this defaults to "No". To my mind, this should never be done (it means that there may be no way for an MUA to automatically identify and reply to author, and our "anonymous list" style does this anyway so it's not necessary for that purpose), but it is often done by discussion lists that want to keep traffic on-list. I recommend you set it to "No" so you don't have to remember the default.
Reply goes to list: No munging
This is preferred by people who discuss sensitive matters (it reduces accidental distribution of mail intended for specific recipients). Strictly speaking, the Internet standard for the corresponding header's use says that it is to be *set* by the author *only*, but many mailing lists set it to the list to "encourage discussion".
Explicit reply-to address: nothing; box is empty
This only affects anything if "Reply goes to list" is set to explicit.
DMARC mitigation action: Replace From: with list address
This is the recommended setting. "None" is impractical because many recipients will reject a lot of mail, which will be recorded as bounces for those recipients (who are doing nothing wrong). "Wrap" is impractical because there are a number of popular mail clients (Apple Mail, for one) which make it almost impossible to read the mail. And reject and discard mean that those authors can't post to your list at all, but they usually can't affect their email providers' DMARC policies.
DMARC Mitigate unconditionally: Yes
This one you should talk to your subscribers and maybe your provider. "Yes" means that *all* posts will have From changed to the "Steve Brown via a-list@example.net" form. An alternative is to set it to "No", which means that the mailing list checks the policy of the author's domain, and changes From only if the domain has a policy of "reject" or "quarantine".
Advantage:
- Some fraction of the posts would have "From" displayed as the author intended it. Depends on policies of your posters' providers. Could be very large if most are academics posting from departmental addresses, could be very small if most are posting from personal Gmail addresses.
There are three possible downsides:
- People from "strict" domains complain about discrimination.
- Subscribers are confused by multiple formats.
- The list's administrative burden increases because Gmail in its infinite disdain for the rest of the world has decided that it does not apply DMARC to mail received by the rest of the world (its published policy is "none"), but it *does* apply it to mail Gmail -> list -> Gmail. I think the most recent versions of Mailman 3 apply the mitigation action to Gmail implicitly, and if not it's simple to add "^.*@gmail\.com" to the "DMARC addresses" setting. The issue is that other providers may think "that's a great idea", and there's no way to find out they're doing it except that you get a lot of bouncers from subscribers using that provider. So you have to monitor bounces.
If you think it might help to change any of those, I'll try it and then roll back if it causes other problems.
That's your call. I do recommend setting "First strip Reply-To" to "No" to make it explicit. All the others except "DMARC Mitigate unconditionally" are the recommended settings for your purposes.
For "DMARC Mitigate unconditionally", I remember a lot of complaints from AOL and Yahoo! users back in the day about "discrimination", but I imagine people are used to DMARC mitigation by now (and of course popular MUAs try to hide it using associations). I've never seen much confusion from the multiple formats, but some people just value consistency in the user interfaces they use. And the administrative burden is likely to be nil unless you're really compulsive about such things -- you just wait for bounces from a random domain to spike and check for "From a@ran.dom" getting bounced by "subscriber@ran.dom", and add "^.+@ran\.dom" to the "DMARC addresses" list if and when it happens. Really only Gmail and Yahoo! are big enough to do this, and most yahoo.* domains already have a "reject" policy.
I also think that a tweak to the T-bird MUA is a strong suspect. The affected subscriber is an old guy like me and in my experience it is also a PITA for him to deal with Mozilla, his email provider (Breezeline), or any other tech intermediary.
Mark: Thanks for the suggestions on searching T-bird emails. I'm going to refrain from passing them on to my subscriber right now as they would probably seem like another PITA.
I agree on that one, although in the long run he'd probably be a lot happier. Another possibility would be to keep a browser tab open on HyperKitty's RADG page, and search authors there. This should work because DMARC processing takes place after archiving in the builtin pipeline, so HyperKitty should know the author accurately. Of course this is suboptimal, but it may be more straightforward than messing with MUA settings (and it works for all MUAs!)
Regards, Yet another Steve
On Thu, Jul 3, 2025 at 12:06?AM Stephen J. Turnbull <steve@turnbull.jp> wrote:
Steve Brown via Mailman-users writes:
"For a while now, my e-mail for this list (but not other lists) just shows "To RADG" from "RADG" with a "CC" showing the actual sender's address.
It's very difficult to figure out what's going on with such an abbreviated description of what he's seeing.
It may be possible to get better results with alterative settings on the list.
In the settings for RADG, under "Alter Messages", what are the settings for "First strip Reply-To", "Reply goes to list", and "Explicit reply-to address"?
Under "DMARC mitigations", what are the settings for "DMARC mitigation action" and "DMARC mitigate unconditionally"?
Because some other members, including me, have had problems with unexpected entries in both From and To lines, I suspect that Mailman 3 does the DMARC enough differently
The only thing I can think of that might allow other lists to have author names for other lists but not for a Mailman list is that the MUAs are parsing email addresses out of the display name (which is a horrible risk, given the flexibility that users have in setting email headers, and especially display names). If there is no email address, then they completely ignore the content of the display name in favor of their preferred display name for the list.
My understanding is that all of the recent posts are missing the poster's name, after behaving as expected for some time. Something must have changed, but what is baffling me. If you have any further ideas, fine, but don't waste a lot of time on this.
MUA "upgrade" seems like as likely an explanation as any. I think if you want to know details what's going on for a particular user, their MUA's support channels are the best bet.
-- GNU Mailman consultant (installation, migration, customization) Sirius Open Source https://www.siriusopensource.com/ Software systems consulting in Europe, North America, and Japan