What are some other resources which might be useful for somebody considering asking a MathOverflow question, especially if their question is not quite a perfect fit here?

In asking this, I have several categories of resources in mind, including but not limited to:

Both online and offline resources; both resources on the Stack Exchange Network and from elsewhere. (E.g. Wikipedia, Zentralblatt.)

Resources for answering questions about mathematics which fall outside of MathOverflow's scope because they are not "research-level". (E.g. Mathematics Stack Exchange.)

Resources for answering questions related to mathematics which are best answered by different communities with non-mathematical expertise. (E.g. Academia Stack Exchange or Computer Science Stack Exchange.)

Other mathematical communities whose expertise may be complementary to that of the community here. (E.g. various discipline-specific mailing lists and discussion boards, or databases such as OEIS.)

Resources for answering questions about MathOverflow or about the Stack Exchange network (e.g. MathOverflow meta or meta stack exchange).

As I've stated it, it sounds like I'm asking for an unimaginably comprehensive list of resources for questions related to mathematics — obviously it would be nigh-impossible to actually compile an authoritative answer to the question as I've framed it. But there's a loophole, in that so far as possible I'd like to address each of these categories of mathematical resources via a meta-category of resources, namely:

- Meta-resources: Lists compiled elsewhere on the internet which themselves compile lists of resources of the above types. (E.g. Collecting math websites is an example of a list of mathematics websites compiled on Mathematics Stack Exchange. Useful mathematical fora is another, focused on mathematics forums.)

long-forgotten, clearly not Athena and Thoth. I was thinking more pre-Columbian deities of the Americas. $\endgroup$discipline-specific mailing lists, you reminded me of this post: Mailing lists / Usenet groups for research math. (It is from 2017, quite a few things might have changed since then.) $\endgroup$