All, Within the last year, Yahoo has published some strict DMARC filtering policies, and Gmail is dutifully rejecting emails that fail the DMARC policies. Unfortunately, this has some negative consequences for other list members, even those without a Yahoo address (in particular, Gmail bounces messages that fail the DMARC checks, and after a certain number of bounces, Mailman unsubscribes the Gmail member from the list). Details: http://wiki.list.org/DEV/DMARC The NUT lists are hosted on Debian's Alioth service, which appears to be running Mailman version 2.1.15. Unfortunately, this is too old to automatically adjust the headers to make the mail appear to be coming from the list server instead of the original sender. I have adjusted some of the parameters, but this is more to keep my mailbox from filling up with the 100+ bounce messages that came in this afternoon. I would ask those who use a Yahoo address to please consider posting from another email address for the time being. As an alternative, you may also open an issue on our Github repository, even if it is more of a question than a bug, and we'll try to get back to you. [Also, sorry for the cross-post: although not yet affected, I included nut-upsdev@ since the problem could also manifest itself there.] -- Charles Lepple clepple at gmail