On Wed, 24 Dec 2014, Tom Yates wrote:
**PLEASE DO NOT REPLY TO THE LIST ON THIS MATTER.**
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As far as I can tell, as summarised at http://postmaster-blog.aol.com/2014/04/22/aol-mail-updates-dmarc-policy-to-r... , a few fairly large email providers have unilaterally implemented a policy called DMARC, and are now rejecting inbound emails that don't meet the policy requirements. In brief, the requirements are based on the content of the From: (the Header-From, rather than the Envelope-From) header line, and basically amount to "no mail may be sent with a From: line that matches our domain, from outside our domain").
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As far as I can tell, the only remedy is to reconfig the list so that the From: address is set to a generic address, probably toasters@teaparty.net, rather than the actual sender (as it is now).
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If anyone feels strongly that the list should be reconfigured as described above, please let me know in the next week or two. If you have strong feelings the other way, it would be useful for me to know that also.
Of those who replied, 60% were opposed to the change, 20% accepted it was inevitable but didn't want it, and 20% were in favour. All seem to accept that DMARC is a complete dog's dinner, being foisted on us by the big email players to solve what is essentially a PEBKAC problem. Several pointed out that later versions of mailman will handle this more elegantly, and I'm grateful for that information, which I'm chasing up.
So at this time I don't propose to reconfigure the list. I've put a warning on the list's page (http://www.teaparty.net/mailman/listinfo/toasters) letting hotmail/yahoo/AOL/etc. users know that they probably won't be able to stay subscribed to the list with their current provider.