You're welcome!
By the way, I manage to make postfix work with the alpine version, but it is configured with tls by default (because of my own configuration).
I'm not a docker guru, but I hope it will be helpful for those who want to use Restyaboard without installing a bunch of stuff on their computer.
For now, I'm not able to change the timezone in the interface, that keeps being UTC (especially annoying in the activity panel), even if I modify the /etc/timezone and /etc/localtime on the container.
Chris