Very well thought out! Rated 5 out of 5 stars
I'm impressed. All the little details are included such as mailto: protocol only linking to one account, and allowing you to set some accounts to notify and others not to. It even has an option to disable the context menu options for less clutter.
Took me a while to figure out how to get automatic logins to work. I had "Clear History" turned on and inside I had "Saved passwords" checked. Untick that and you don't even need Firefox to remember your passwords. It will remember you without that option (clearing Cookies and Active logins is OK too.)