The short answer is...
No, not with the system as is. That is
because there is a statistic for the number of messages in mail.box waiting
or dead. But there is no individual statistic for each message sender.
Which is what you would need to do what you said. In order
to do that, you'd have to create an extension manager hook on the note
create function when executed in mail.box and then create a statistic unique
to that sender. Then create a statistic monitor to check the stats
and see if it passes a threshold.