Good question CO.
If you subscribe to a Mystery Box thread, your subscription will be to that Mystery Box thread only.
There are never any new posts in the MB threads because those threads are closed.
MB threads only contain the one root post for all the Mystery Box girls originally requested in that year.
These are all older posts that will not trigger any notification.
Any new posts for MB girls go into what we call MB Followup threads.
The MB Followup threads are in the Mystery Corner sub forum.
MB Followup threads are separate threads, which have a link connecting them to the root MB post.
The MB root post should have a link to the MB Followup thread (if there is a followup thread)
MB Followup threads are open to new posts.
If you want to receive notice of new posts on your MB girl, you need to subscribe to her MB Followup thread (if there is one).
Then you will see any new posts on her ID request.
Some MB girls do not have an MB Followup thread.
Usually because no one posted any further info or content.
If there is not currently an MB Followup thread for the MB girl you want to follow, you can start one, by starting a new thread for her in the main Model Identification Request forum
here.
The first post in
this thread, describes starting an MB Followup thread, along with much more info concerning Mystery Boxes and MB Followups.
Please include a link to the MB post you want a followup thread for.
When we see your post, we will add a link in the MB post to the MB Followup thread you started.
If you need help more help, contact me, or any an MIR mod.