Robin,
if we DO NOT TICK “dashboard>settings>forums>Allow users to subscribe to forums and topics”
will all users be subscribed to all forums and all topics??
This functionality has been available in Joomla’s Kunena Forums since around 2010 or 2012.
I’m kinda sorry we changed our website over to WP since it’s the one failing I get the most complaints about now that we ARE on WP. AFAIK there was no extra cost to have the function in the Kunena forums. Darn! and it worked perfectly too.
Did you say your name is Sisyphus ? It would seem so..
You might want to read this article, (I don’t know how old it is or how current the advice..)
https://codex.wordpress.org/Post_to_your_blog_using_email