Exchange 2003 - How to limit number of INCOMING recipients

Factual Questions
1

I know that you can limit the number of recipients for outgoing messages, but is there a way to set an upper limit for incoming messages?

Background - an inappropriate email was sent in to one of my company’s distribution list addresses. We have corrected this by only allowing validated users to send to our distribution lists. However, there is noting preventing someone from sending another email like this to everyone individually.

So is there a way in Exchange to disallow incoming emails if the total number of addressees is above a certain number? I have looked online but I only find ways to limit the number of outbound addressees.

2

But surely you’ll be receiving one email per recipient? The emails are generated by the remote end, not your end. So you want some sort of mail filtering software between the Internet and your Exchange server. Something like Mailwasher, perhaps?

3

Back when I had to worry about this thing, I worked at two different companies that used the Barracuda appliance. I believe – but can’t say for sure – that their software handles this sort of scenario.