We have Exchange 2010 SP1. It uses an SMTP relay server to send messages through. That server allows us to send 300 messages per day. We usually send about 70 messages of them.
Suddenly today, 300 messages were sent so we can't send anymore messages. I have increased the quota to 450 to solve this. But in less than an hour, those 150 messages were used !
I think there is some computer infected with a virus inside the network.
The question: How to track which users have sent messages through exchange in the last 24 hours?