Rated 4 out of 5 stars

I moved to Thunderbird from MacOS Mail and was looking for something to replicate the functionality of the excellent MailTrackerBlocker (MTB) by Aaron Lee. PixelGuard is a good attempt, but lacks some of the precision of MTB. Some of the images it identifies as tracking pixels clearly are not. However it does show each identified tracking pixel, non-tracking image and link in its detail view so that one can perform one's own diagnosis.