turn off e-mail notifications for all users by default

How do I prevent automatic notifications (about replies to topics, etc.) from being sent to my users automatically? Will they need to disable these notifications manually?

I especially need to disable any sort of function that automatically makes a user start "watching" a topic without asking permission first.

Can't be done.

so anytime a user posts in a thread, they're automatically watching it?

Correct, all users will need to do it via thier Profile.

where is that option?

Profile>>Peferencess>>Look for Always notify me of replies :>>No>>Save

thank you!