Sniffing Mail Traffic - Outlook --> Exchange Server

Dear list,
I wanted to demonstrate to management that traffic in clear text are vulnerable to sniffing, and to do this I wanted to sniff mail traffic:

I am trying to monitor the traffic between my Outlook Client and my Exchange (2003) server

Normally the protocol used for communication is IMAP, which is not encrypted

However wireshark gives we traffic log for only TCP and DCERPC protocols

Could you please help? Am i missing something here?

Many many thanks