Limit users from sending too many emails - exchange 2010

HI,

Exchange 2010 environment. From time to time, marketing people do mail campaign and send out massive amount of emails, 500+ at a time. Is there a way to set limit say, for a user or a server to only allow 100 emails out at a time. Hub transport server relays this to a unix box and because of this, it causes the mailq  on the unix box to grow and cause performance issues.

Thanks!

Joe.