works with this update Rated 5 out of 5 stars

Please go to this link http://webmailnotifier.mozdev.org/installation.html [developer's home page] and download section->
WebMail Notifier 2.9.12 - 2012-08-17

fixed gmail script
updated hotmail icon
updated forum links

Install the update and restart firefox.

Hope this helps!

This review is for a previous version of the add-on (2.9.11).  This user has a previous review of this add-on.