My email account is filled with replies to threads and I cannot see where I stop this
It is rather annoying to say the least
Go to the 'Quick Links' menu at the top of the page just below the banner, there's a 'subscribed threads' link. Clear your subscriptions if you don't want email notification every time someone posts in them. Also go into 'General Settings' and set the ' Default Thread Subscription Mode' to Do Not Subscribe. That should sort out your inbox getting filled.