Recently, we found that there is a performance issue of our email server, it seems there are many emails sending or receiving from the others, can I monitor it and knowing which IP(s) is/are sending or receiving files from the email server?.. I have tried Sniffer from NAI, it seems it can only monitor the traffic from Sniffer machine to email server!... Can anyone help me!? Can you leave me a detail way to monitor it?..
p.s. my email server is running under Digital UNIX