Monitoring multiple mailboxes

Hi, Was wondering if it is possible to monitor multiple mail boxes?
I have this in-house application that I am developing and I would like it to subscribe to multiple WMI. I was thinking to either specify multiple mailboxes for that user agent in sip.conf or just have my application issue several SUBSCRIBE. But with the later method, I only get 404s because I guess asterisk won’t let me subscribe to mailbox notifications that are not tied to my user agent.

Thank you.