For some reason it did not send out verification e-mail after registration, but sent it immediately after i send forgot e-mail form at https://forum.nginx.org/login.php

I have suspicion that i tried to register before and same happened. Maybe you can verify this yourself. Btw. verification e-mail is sent by nginx-forum@forum.nginx dot org (added spaces for protection), yet that User doesn't exist
And the site has no contact form.