If you click the Notify button in a topic then you will receive email notifications when there are any new posts in that topic.

So it would appear that you have subscribed (the notify bit I mentioned) to a topic, this one View the reply at: http://forum.avast.com/index.php?topic=74566.new;topicseen#new.

If you no longer want to be notified of new posts then unsubscribe, this one.

Unsubscribe to this topic by clicking here: http://forum.avast.com/index.php?action=notify;topic=74566.0

The last bit simply means if you unsubscribe you can post in that topic or others can post/reply in that topic, but you won't receive the email notifications if anyone replies.