Rated 4 out of 5 stars

UPDATE: I believe the password requests were coming from Thunderbird and NOT this extension. If you are having trouble with password dialogue box floods, you can disable your master password by going to Tools > Options > Security > Passwords and UNcheck the master password option. Leaving my full review up in case anyone else has trouble with Thunderbird.

This extension worked great the first couple of days. Now, it continues to spam me, asking me for a password. I've messed with the settings, and even uninstalled it at this point, yet I keep getting flooded with dialogue boxes "Password Required: Please enter the master password for the Software Security Device."

Use Master Password+ if you really need a password for Thunderbird, and if you're willing to deal with the flood. Otherwise, avoid.

UPDATE: Again, the flood came from Thunderbird's master password option and NOT the Master Password+ extension.

This review is for a previous version of the add-on (1.21.3.1-signed).