In the connections area it lists the IP address, port, and connections. I have one connection (port 143 -- IMAP) that shows 11 connections (this seems excessive when all the rest are 1 or 2).
When I look at the User Activity it list the users with the information. Only the IP shows for Webmail. I can tell the user in this case as they have 11 connections.
It would be nice if the IP address showed for all of the rows.