I don't know if this is a problem with Vanilla being behind proxy, I setup Nginx as described in the docs.
But there is problem some URLs emitted by Vanilla lack the hostname part of the url.
Is there an option to force the hostname part? I would like to set it manually then everything would be ok.
I also noticed it happens on the test email also...
The message i receive looks like that:
"This is a test email message.You can configure the appearance of your forum's emails by navigating to the Email page in the dashboard.
Check it out: https:///index.php?p=/"
Not sure to which documentation you are referring. I use the rewrite like that: https://open.vanillaforums.com/discussion/comment/247990/#Comment_247990
But I also found such a configuration: https://open.vanillaforums.com/discussion/comment/247680/#Comment_247680