Almost everything at Apache uses a mailing list to get work done. People can send mail to the list, many other community members get the message, and someone will usually reply. Every mailing list at Apache is archived: most lists are archived publicly. That means that newcomers to a community can learn how decisions on a project were made in the past, because all the discussions a project had are archived from their mailing list discussions.
If you have questions about anything at Apache, the first thing to do is find the right mailing list - and then send your question!
Detailed instructions on how to use Apache mailing lists (subscribing, sending mail, reading the archives) are posted on our main developer site. You can email most lists without subscribing, but some lists require subscription first. Most emails are moderated, so it won't show up on the list immediately, you may need to wait a day, especially if you are new.
Please be sure your question is on topic for the list, and that you have at least checked the documentation first: everyone at Apache is a volunteer, and if you don't do your homework, we probably can't help you.
Finding the right list helps get your question in front of people who will know the answer. Every project at Apache uses their own dev@, user@, and other mailing lists - so asking about Apache Tomcat on the Apache Cassandra lists is likely going to be ignored.
Projects should have a Mailing Lists, Community, Contact Us link on their homepage, start there.
If you have any non-technical questions, or a general question about how Apache works, then you should check our Apache-wide mailing lists, or just ask here on firstname.lastname@example.org!
Almost every list at Apache is archived publicly. This is a great way to learn about how a community has done things in the past, or to learn about why a project operates the way they do. The ASF maintains an official archive, which is guaranteed to have all emails, but is a bit clunky:
Several other organizations also archive many/most Apache mailing lists, and some offer useful search or sending functionality: