Actually there is: when you post a new topic, under options at the bottom there is a checkbox for enabling email notification.
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
Note that you can only be alerted on topics you yourself create. I am not sure if you can change it later - i've never tried. Some people have mentioned here that they got alerts on threads that have not been active for years when somebody digs them up and makes a new post, and that causes a flurry of posting activity.
Just something to consider.
There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors