I dared not to open that particular thread for a week, still the email arrives with every new post added there.
The choice of notification emails in the settings (linked earlier) works in a funny way.
I selected NONE, and it actually works. All
newly subscribed threads since then have NONE email notifications, but alas the previous still retained the INSTANT method. I actually changed to WEEKLY for testing deeper, and it works - again only on the later-than-the-change subscribed threads.
.
Hence this situation (threads listed from the most recently updated ones)