Rated 3 out of 5 stars

Just a temporary replacement of RefControl, and you need a better icon!

This review is for a previous version of the add-on (0.40.1-signed.1-signed). 

This is not meant to be a replacement of RefControl but rather a complement. CRB works with a global Firefox/Thunderbird setting while RefControl controls referer on a per-site basis.

As for the icon, I am not an artist but if you think you can create a better one, use the Support Site to send your creation and I will consider using it instead.