As Prof. Marks mentioned, I also suspect that it is due to gmail [1] and
mail.ru [2] recently changing to a stricter DMARC Policy (i.e., from
p=none to p=reject).
The DMARC reject policy (p=reject) is known to be a problem that is not
easy for mailing list administrators to address [3], because it
currently seems that a choice has to be made among a list of imperfect
solutions that come with their own pros and cons [4].
For an administrator of a mailing list (Mailman), the possible solutions
listed on the webpage that should be accessible as follows might be of
interest:
1. Go to: https://wiki.list.org/
2. Click "List administrator tasks" (under FAQs in the left menu)
3. Find and click on "What can I do about members being unsubscribed by
bounces of Yahoo user's posts for DMARC policy reasons?"
[1]
https://dmarc.org/2015/10/global-mailbox-providers-deploying-dmarc-to-protect-users/
[2] https://team.mail.ru/why-mail-ru-implements-a-strict-dmarc-policy/
[3] https://wiki.list.org/DEV/DMARC
[4]
https://dmarc.org/wiki/FAQ#I_operate_a_mailing_list_and_I_want_to_interoperate_with_DMARC.2C_what_should_I_do.3F
_______________________________________________
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
