Rated 1 out of 5 stars

This abysmal add-on was bringing my system to a crawl. The hard drive was constantly chattering chattering chattering and I could not figure out why. There was lots of CPU activity for Thunderbird, and finally Procmon showed hundreds of access per minute by Thunderbird to TestPilotErrorLog.log and files in the TEstPilotExperimentaLog or some such folder. Googled and found out about "Test Pilot." Removed it and all is better. While it was installed it took 10-15 minutes to restart Thunderbird because it was accessing these files for several minutes after the GUI unloaded. Very disappointed in Mozilla for putting this on my system. Would give it 0 stars if I could.

This review is for a previous version of the add-on (1.3.9). 

If you've still got a copy of the log, please could you file a bug under the Thunderbird product on https://bugzilla.mozilla.org and attach an extra of the log. I suspect there's something that has gone wrong in your particular situation and obviously needs fixing.