Migrating existing lists from Mailman 2.1 to Mailman 3

Responsiveness and throughput of all functions

Plugin handling, specification, and integration, including internal APIs

Privacy, denial of service, authorization, authentication, mail flow filtering

Subscribing and unsubscribing from mailing lists

Code and APIs needing refactoring or generalization

Unit, doc, and integration tests

General usability issues for all users

Non-urgent feature requests for future reference