[MM3-users] Guidance Request: Migrating Existing Mailman 3 Installation to Docker-Based Deployment

Hi all,

I am currently running a Mailman 3 setup on a standalone server and planning to migrate it to a Docker-based deployment using the official Docker Mailman images. I would appreciate your guidance on the recommended approach for this migration.

*Current (existing) setup:*

• Mailman Core: 3.3.5
• Postorius: 1.3.6
• HyperKitty: 1.3.5
• PostgreSQL: 12.22 (Ubuntu)
• Host-based installation (non-Docker)
• Postfix used as the MTA
• Active mailing lists with members and archives
• Apache reverse proxy in front

*Target (new) setup:*

• Docker-based Mailman 3 (mailman-core, mailman-web, PostgreSQL containers)
• Based on the official Docker Mailman repository
• Postfix as the MTA
• Apache reverse proxy in front

I would like to migrate the following components safely:

• Mailing lists and their configurations
• Subscribers and roles
• HyperKitty archives
• Postorius/web data (users, preferences, etc.)

I have a few specific questions:

1. What is the recommended migration approach from a host-based Mailman 3 installation to the Docker-based setup?
2. Is it safe to directly restore the PostgreSQL databases into the Docker environment, or is there a preferred migration method?
3. Are there any version compatibility considerations when migrating from Mailman Core 3.3.5 / Postorius 1.3.6 / HyperKitty 1.3.5 to the versions used in the current Docker images?
4. How to migrate archives?
5. The official Docker Compose file references postgres:12-alpine. Is it recommended to stay on PostgreSQL 12 for compatibility, or is it supported to use a newer PostgreSQL version (for example, PostgreSQL 18) with the Docker Mailman setup?
6. Are there any common pitfalls or best practices you would recommend for ensuring a smooth migration?

Any guidance or documentation you can provide would be greatly appreciated.

Thank you for your time and support.

Kind regards, Prasanth Nair