We moved a 40,000-list installation to Mailman 3 over a single weekend. Here is what the plan looked like and where the real risk lived.
Most migration failures are not technical. They are the small assumptions nobody wrote down, surfacing at 2am.
Affinity rebuilds the Mailman 3 admin around the one screen list owners live in: the moderation queue.
Empathy indexes decades of list traffic so a subscriber can find the one thread they half-remember from 2011.
List mail breaks sender alignment by design. Getting delivered in 2026 means handling that on purpose, not by luck.
Shared hosting is fine until a neighbor gets your IP blocklisted. For lists, isolation is a deliverability decision.
Aggressive bounce rules shrink your list. Loose ones wreck your reputation. The tuning is the whole game.
The right tier depends on volume, sender reputation needs, and how much moderation your lists actually do.
