http://forum.[ simutrans [dot] us (site down, do not visit) ]/
Basically, just save that address somewhere.
DO NOT USE THE BACKUP FORUM IF THIS FORUM IS WORKING. It's to serve as a backup only...
Basically, over the past few years, there have been a handfull of times that it would have been handy to have a backup place to talk about the server when there were problems (in all cases I can think, when I had some sort of problem with my server, or whatever)... And so now I created such a place... :)
But it is not a forum replacement, and if the forum is up, posts over there will be removed. Please do not feel a need to fill up the empty space with anything!
...but if the main forum is ever down, check there for news. (And if you cannot get to this forum, feel free to ask about it over there...)