BALUG.org (lists.balug.org)'s lists migration from Mailman 2 to Mailman 3

Things you'll generally want to be aware of regarding the migration and changes:

• included in migration: migration of existing subscriptions and most member/subscriber options
• migration does not create a login account nor password for such (and no more password reminders nor storing of password in clear text - yay!)
  • you will generally want to create a Mailman 3 login account (if you haven't already) via Sign Up and may do so at any time. Note that those are per site, not per subscription, so one such login can be used to manage all one's subscriptions - one can even have a login without having any subscriptions. One can also associate multiple email addresses with the same login if one wishes to do so.
  • With Mailman 3 login account, one does also have access to some pretty spiffy features not present with Mailman 2. E.g. if one is subscribed to and can post to list, can do that via the Mailman 3 web interface directly.
• One can view and manage subscriptions and options, etc. via login account.
• Unless otherwise stated, generally indicates generic changes in going from Debian mailman 1:2.1.29-1+deb10u5 to mailman3-full 3.2.1-1 and associated packages (most notably dependencies)
• One can also manage subscriptions via mail, however the Mailman 3 mail interface is much more limited compared to Mailman 2 (e.g. one can't view or alter list options such as plain text or MIME, digest or not, etc. via mail interface with Mailman 3). What that mail interface basically does offer:

managing subscriptions, etc. via mail
If the list posting address is LISTPOST@LISTDOMAIN, e.g. balug-test@lists.balug.org
one can send help and other commands to LISTPOST-request@LISTDOMAIN, e.g. balug-test-request@lists.balug.org
One can also use LISTPOST-subscribe@LISTDOMAIN and LISTPOST-unsubscribe@LISTDOMAIN respectively to subscribe or unsubscribe.
Mailman 3 (notably -request address) will take commands from Subject (if present) and then Body of the mail message,
and end or stop can be used to indicate no further commands (e.g. to ignore an automatically added footer/signature, rather
than try and process it as additional commands).  These are the commands the mail interface supports:
help        - Get help about available email commands.
subscribe   - Subscribe to this mailing list.
unsubscribe - Unsubscribe from this mailing list.
confirm     - Confirm a subscription request.
echo        - Echo back your arguments.
join        - An alias for 'subscribe'.
leave       - An alias for 'unsubscribe'.
end         - Stop processing commands.
stop        - An alias for 'end'.
addresses of the form LISTPOST-join@LISTDOMAIN and LISTPOST-leave@LISTDOMAIN
may also be used for subscribe/unsubscribe.
Note that subscribe and unsubscribe generally require confirmation (to generally avoid misuse from The Internet by others).

For folks that may be interested in seeing lots of the planning and testing details for BALUG's Mailman 2 –> Mailman 3 migration, may want to have a peek here: https://www.wiki.balug.org/wiki/doku.php?id=system:mailman3