Disabling email notification of replies

Could someone please tell me how I can turn off the sending of “Recent activity on your discussion subscriptions” emails from TechRepublic, of which I’m receiving dozens a day. I wouldn’t mind (and would actually like it) if one was sent on the first reply to any thread, but no more until I visited the forum. Being bombarded with identical emails is seriously annoying and either I’m blind or there doesn’t seem to be any option on the user settings page to turn off these notifications.