Rated 5 out of 5 stars
This is a very useful addon if you are a web administrator of any sort. You can easily see what email client the user is sending mail with, and quickly deduce what OS they are using. With this information, you can more easily assess their situation if they need technical assistance. I love this addon because it helps me immensely.This review is for a previous version of the add-on (1.6.8).