How safe is Webmail Notifier for Firefox 3.0?

I just installed Firefox 3.5 in order to clean up a very serious bookmarks problem I had. At first I thought I'd hate it but I really love it now. So I downloaded a few add-ons and one of them was Webmail Notifier.

I downloaded it from within the add-on link in the firefox dialog box that was produced. In anycase I installed it, restarted firefox, and set it up. But before I put any personal information in I wanted to know how safe it is? Is it ok to use as it will make my life so much easier or is it a death trap waiting to happen?

 

This one? https://addons.mozilla.org/en-US/firefox/addon/4490

I used to use it and never had any issues or concerns.

 

Yep, thats the one. It would make my life so much easier.