I now get subscription alerts.

How do you subscribe to a thread without posting to it?

Go to the top of this post by RedneckDude.  Notice the icons on the bottom right.  Click on the star.

Ah, there it is.  11 pages back.  Thanks!

"Subscribe to this post" and "Email me when someone replies" are both tagged, by default.
Posts show up under "Profile > Subscriptions" > "You are currently subscribed to ... posts"
My email address is correct. 
Under
However, when posting I never get any notifications 
BTW, there is nothing in my spam box either.

I need to check manually whether there are any replies.

Later:
I am sorry, I should correct the above, because it is not entirely true.
Actually, I did receive a notification on the forum thread "How to copy existing configuration to a fresh Windows 11 / Start11 install"
(apr 24), so at the time it worked.
Later posts, different other threads: no notifications.