As you might guess, the most popular of the nms programs is formmail. We're just starting to see one of the downsides of that popularity.
Some people who are setting up formmail on their web servers are misconfiguring it. As a result the emails aren't being sent to the address they want, but to the nms support mailing list. This is slightly bizarre as that's not the default destination or anything like that. They're actually configuring the script to sent email to us rather than them.