I liked a lot this extension.
I didn't found any other that could do what I need.
Changing a little bit the code, I could make that any user can see the last messages of a gmail IMAP account.
Cons: I get an empty page when I try to open an email with atachments. Maybe because of my modifications? And when I see a message from a pop3 account the message are removed from the list (marked already downloaded). Any ideas?