Once upon a time, I'd receive an email notification if someone posted on a topic I'd flagged; no more, and suspect it's down to something I've changed in my profile? Had a look and can't see what it might be.
Also, is it possible to delete all watched topics in one go?

As I understand it, to delete ALL watched (topics you have posted in) .... go to your PROFILE in top blue banner on page. Then under black banner Advanced Information and Preferences, go to 3rd line down and select NO.

Now to stop email replies on selective topics, when replying to a post ..... just before you press SELECT, see the button above it make sure its NOT ticked.

I hope this helps, but should I have got it wrong, can someone tell us both where ??

Thanks for the reply; had already done that and believe that'll stop future problems, don't see that it's a way to delete everything in one go. It is possible via Profiles to delete singularly but I seem to have pages of items