TLDR: Mailman3 is now available for general use, all mailing lists will be migrated in the next couple of weeks, providing everyone with a much better mailing list experience. You will notice some changes, let us know if you run into issues.

Long version:
We're happy to announce that Mailman3 is available for general use and some have already been migrated. You can find the current mailing lists that have been migrated at [1] and their archives in "hyperkitty"[2].

Mailman3 is a full rewrite of our previous mailing list software (Mailman2), and the migration is long overdue. Some key new features that we want to highlight:
* One user account (no more monthly password reminder emails or list passwords)
* Ability to search through archives
* Posting through a web interface
* A web interface that doesn't look like its from the early 2000s
* Better security of accounts and messages

The first mailing list migrated was LGBT@ and you can see its mailing list page in [3]. We are going to slowly migrate the rest of mailing lists (all +700 of them), you can track the work in [4]. All new mailing lists from now on will be only on Mailman3.

This means:
    * We will send an email to admins of any mailing list right before starting the upgrade process, and once it's finished.
    * The link to subscribe to lists will change, please update your wiki pages, documentation, etc. We will provide redirects though.
    * Links to old archives for public mailing lists won't break. It will stay at it is now and will become redirects shortly. But URLs of archived emails of private mailing lists will break. This is necessary for improving security of mailing lists. Keep it in mind that in the new system you can easily search in the archives.

Given that in Mailman3, you can simply have one central account for all of your mailing lists. We highly encourage you to make one [1], that way, you can easily control what mailing lists you are subscribed to, easily join new mailing lists and much more. This also makes administrating and moderating mailing lists much easier.

If you have any questions or you encounter any issues, let us know! You can create a Phabricator ticket ("Wikimedia-Mailing-lists" project) or ping us on IRC in #wikimedia-tech.

We hope that Mailman3 brings much needed love to our mailing lists without breaking your workflows (like reading mails by piping telnet into less or something like that).

The umbrella ticket for the work: https://phabricator.wikimedia.org/T52864

[1] https://lists.wikimedia.org/postorius/lists/
[2] https://lists.wikimedia.org/hyperkitty/
[3] https://lists.wikimedia.org/postorius/lists/lgbt.lists.wikimedia.org/
[4] https://phabricator.wikimedia.org/T280322

Kunal (Legoktm) and Amir (Ladsgroup)