Repeated email notices about comments

In the last several days, when one of my students leaves a comment, I'm often getting repeated emails sent to me informing me about the new comment. For instance, I logged on to ID a few minutes ago, noticed a student's comments were in the Spam folder, approved them, and I've received email notices about his new comment at 11:43 am, 11:46 am, 11:49 am, 11:52 am, 11:55 am, 11:58 am, and so on. Every three minutes.

How do we make this stop?

Thank you.

Scott