The long-term solution would be to implement T316349: Replace the on-wiki Wikimedia nomail list page with a global preference.

Do you have any specific examples (even if in private)?

Was it everyone? Only a couple of users?

For example, the regex (/(?<=<pre>).*(?=<\/pre>)/s) against the page, very superficially suggests no matches... https://regex101.com/r/XKG7wY/1

The <pre>/</pre> tags have been removed at some point... Which will explain it not working!

https://meta.wikimedia.org/w/index.php?title=Wikimedia_Foundation_nomail_list&diff=prev&oldid=26153633

Change #1071631 had a related patch set uploaded (by Reedy; author: Reedy):

[mediawiki/extensions/SecurePoll@master] makeMailingList: Check we get some users on the nomail list

https://gerrit.wikimedia.org/r/1071631

In T374310#10130266, @Reedy wrote:

https://meta.wikimedia.org/w/index.php?title=Wikimedia_Foundation_nomail_list&diff=prev&oldid=26153633

D'oh! That would do it.

Maybe the script should still be tweaked to look for something that's not the <pre> tag anyway?

In any case I wrote a small Python script that fully removes those folks from the mailing list I have at the moment (the nomail list check is done in the compilation of that list, so these improvements wouldn't impact this cycle anyways)

In T374310#10131440, @jrbs wrote:

Maybe the script should still be tweaked to look for something that's not the <pre> tag anyway?

It's a little hard to know what is a username or not otherwise based on how the list is currently; Is {{Process header etc? We don't have * prefixes, for example like we do in other places.

In T374310#10130272, @gerritbot wrote:

Change #1071631 had a related patch set uploaded (by Reedy; author: Reedy):

[mediawiki/extensions/SecurePoll@master] makeMailingList: Check we get some users on the nomail list

https://gerrit.wikimedia.org/r/1071631

^ Primarily, that is what this does though.

If we don't get any results from loading https://meta.wikimedia.org/wiki/Wikimedia_Foundation_nomail_list, that's almost certainly going to be an error based on the current implementation (the page name isn't variable etc), and it will abort at that point, and not (finish) making said list (arguably, if it's going to fail, it's going to fail very early, after the first user it finds that has a confirmed email... And if they have no email set, they're not going to have been written to the list to be emailed anyway)... With a fairly visible error.

Change #1071631 merged by jenkins-bot:

[mediawiki/extensions/SecurePoll@master] makeMailingList: Check we get some users on the nomail list

https://gerrit.wikimedia.org/r/1071631