There have been numerous reports of a multitude of emails being sent to a member's inbox notifying them about replies. This is quite the annoying feature, but there is no way to disable it for all members. However, individual members can disable it by going to "Profile>Preferences>Display a notification when new replies are written" and change it from "Yes" to "No".
This may be only temporary, as I am contemplating switching the forum from phpBB3 to Invision, but it is worth noting just in case.
Also, on a unrelated note, the minimum character limit for topic titles has been receded to one character instead of ten.