Cisco Call Manager - FreePBX for Voicemail

I was able to get Exchange 2010 working with FreePBX IMAP Voicemails to the extent that voicemails get sent directly to my Exchange 2010 inbox. I am having a problem however with using externnotify and pollmailboxes option. When I read or delete a Voicemail from my inbox, MWI does not change. It seems that when I use my email application to delete voicemails, the externnotify script is not called.

Do I have the wrong impression of what pollmailboxes should do? Is anyone using pollmailboxes and externnotify together succesfully?

-Brendan