Damsel in Distress

The damsel? Yeah. That’d be “yours truly” (uggh, how I hate that).
The distress? (See below.)
This plea for help goes out to anyone who has Movable Type and knows how it all works. I posted this on the Technical Support/General Problems board, but no one has responded yet. I am impatient, and I want help now.
Here is the challenging question I posed in the forum:

Everything was just groovy until sometime last night when all of a sudden … POOF! … I stopped receiving email notification whenever I received a new comment on my fabulous site.
A friend of mine checked my MT paths and all that jazz (you will note that I am not “techy”), and said that everything is configured properly. Still, no email notification.
There is nothing wrong with my email otherwise; I’m receiving outside email juuuust fiiiine. But the MT stuff? Nyet.
Can anyone help me?

So … can any of you help a poor delicate flower in her time of need?