[Mailman-Users] "Prevent" Reply-all

Ryan C Stasel rstasel at uoregon.edu
Tue Oct 25 19:55:45 EDT 2016

> On Oct 25, 2016, at 15:42 , Mark Sapiro <mark at msapiro.net> wrote:
> On 10/25/2016 02:46 PM, Ryan C Stasel wrote:
> There's not much you can do with list configuration.
> Mailman ensures the list posting address is always in To: or Cc:, so you
> have to modify code (Mailman/Handlers/CookHeaders.py) to keep it out.
> You also may need to set the list's Non-digest options -> personalize to
> Full Personalization so the list address is not in To:.
> Perhaps a better way to do all of this is to set the list's Non-digest
> options -> personalize to Full Personalization and create a custom
> handler (see <https://wiki.list.org/x/4030615>) to go in the pipeline
> after CookHeaders and to just remove any Cc: from the message. Then the
> From: will be the poster, To: will be the individual recipient and there
> will be no Cc:.
> However, with any method like this, you will run afoul of DMARC if the
> domain of From: publishes a DMARC p=reject or p=quarantine policy. You
> really can't avoid DMARC issues without changing the From: domain.
> Standard DMARC mitigations will probably work by putting the original
> From: in Reply-To:, but then you have the issue of the munged From:
> containing the list address and you'd need to change that, but to what
> could you change it that isn't the original From:, isn't the list
> address, won't bounce and won't inundate someone with unwanted mail,
> Maybe the list-owner address?
> Another way to do something, but not exactly what you ask is to set
> Privacy options... -> Recipient filters -> max_num_recipients to 2 and
> require_explicit_destination to Yes.
> This will ensure that any post which addresses more than just the list,
> which all reply-alls will, will be held for moderation.
> For more control, you can use header_filter_rules to hold or reject
> posts with more that one address in To: (a regexp like '^To:.*?@.*?@.*$'
> might do although it will falsely catch a display name with an @), or
> any Cc:

Hmm, darn. I might play with the max recipients thing, but I think the end result of that will be similar to just making the list moderation only. 

Thanks Mark! 

-Ryan Stasel

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