@[email protected] Thanks for your detailed answer.
The analysis and suggestions are all reasonable. I went with your option #1, and it worked well. I appreciate your prompt help.
One thing I didn't mention, the registration applications page was empty, but after both admin and non-admin users are verified, I'm able to see and approve the applications.
I've also removed postfix-relay from docker-compose.yml as I think it's now useless. It could be an optional component in the Ansible playbook.
I started taking long breaks from social media apps a year ago and have been using the time to read more books instead. I did go on Mastodon and Lemmy later, but overall I feel better than before.
Recently I finished the book Digital Minimalism https://mementomori.school/post/1996 as I'm interested in this topic. I got the video recommended by the YouTube algorithm after watching a few videos from the author. I hope his ideas can be helpful to you.