dap1--- via Mailman-users writes:

I am about to migrate from mailma2 on CentOS to mailman3 on Ubuntu. Are there any special gotchas of which I need to be aware? TIA.

• The Ubuntu packages are old, and not well-supported by Ubuntu or the Mailman project. Mailman 3 is not a hyperactive project, but we are making steady progress and many new Mailman 3 users have issues or requests for enhancement for 2-, 3-year-old packages that have been fixed or implemented in the most recent releases. For these reasons, we strongly recommend installing from source or from PyPI in a virtual environment: https://docs.mailman3.org/en/latest/install/virtualenv.html#virtualenv-insta... (Installing from source is not hard, but it's more work than using pre-built packages. Source is required for beta testers and developers, but not recommended for most production environments.)

• If your preferred RDBMS is in the MySQL family:

1. Make sure the Mailman database(s) have the utf8mb4 charset option set. Otherwise all emoji and some Asian characters will cause your database to throw errors (I think this is mostly an issue for HyperKitty and maybe a few users who put them in their display names in Postorius and Mailman core). This is not needed for PostgreSQL or SQLite3.
2. You may want to increase the timeout for startup (I think this is in the systemd units for mailman and mailmanweb). The issue is that the mysqld doesn't exit until the journal has been flushed to the main database (or something like that), and this may take many seconds. This is not an issue for SQLite3 (it's a library) or PostgreSQL (it uses dbus to notify systemd that it's ready).

• The migration scripts for list database and web databases are quite good, but not 100%.

• The user model is completely different. Ordinary subscribers will probably be happy or won't notice, but there are some traps for administration roles. The most important is that some list owners will give the owner password to moderators so they can do work like use mass subscribe, but put them on the moderator list attribute so they get the moderation notices. These moderators will lose the "owner" capabilities like mass subscribe.

• If you're looking at a multinode installation with Mailman core, Postorius and HyperKitty distributed across several hosts or containers, configuration can be finicky. I don't recommend it unless you're familiar with such distributed operations.

Steve

-- GNU Mailman consultant (installation, migration, customization) Sirius Open Source https://www.siriusopensource.com/ Software systems consulting in Europe, North America, and Japan