Requires little time and effort if you have requisite knowledge. Related to but different from "beginner-friendly".

Requires little knowledge of Mailman internals to work on. Related to, but different from, "easy".

User questions with no changes required in the Code

Related to the REST protocol use for communication with the Mailman core. You probably should not use this; such issues usually are specific to mailmanclient.

The UI makes things hard to do, or doesn't provide an operation.

Internationalization, including words that should be translated but aren't (bug) and languages that aren't available at all (wishlist).

Bug

Integration with alternative mail servers, WSGI servers, and other external services

Website, wiki, repos, tracker, mailman-* making lists

Plugin handling, specification, and integration, including internal APIs

A candidate for backporting to a point release, if we decide to do one

Shell commands and subcommands (i.e. `mailman`)