Are you sure the setting "instantly, using email" at "Default Thread Subscription Mode" does not work?
You can find this setting on
http://forum.sanriotown.com/profile.php?do=editoptions (or click on "Top" on the right side just below this post, click on "Settings". On the "Settings"-page please choose/click "General Settings" below the menu-title "My Settings"
on the left side of the page in the menu.
Scroll down to find the "Default Thread Subscription Mode" and choose either "instantly, using email" or "daily, using email" or "weekly, using email" using the drop-down menu-arrow to the right of the empty box.
It says there: "When you post a new thread, or reply to a topic, you can choose to automatically add that thread to your list of subscribed threads, with the option to receive email notification of new replies to that thread."
You can find all of your subscribed threads at
http://forum.sanriotown.com/subscription.php or by clicking on "My Subscriptions" in the left-side-menu on the "Settings"-page.