I know what I said! is a post on The Hickensian

Quick Movable Type hack. If you ever reply to users who’ve left comments on your site – you’ll get a email notification the same as you do for every commenter. Via the Movable Type support forum, I found a way of stopping it. Go to lib/MT/App/Comments.pm in your MT folder. Find the line that reads:

MT::Mail->send(\%head, <

MT::Mail->send(\%head, $body) unless $author->email eq $comment->email;