But does it ask when you try to send or get new messages? That is what it is for. If you want to secure your message store, you need to go about it in another way. But why not just set up a user account with a password in your OS and secure ''all'' your personal data? http://kb.mozillazine.org/Protect_the_profiles_contents I'd like to add my own suggestion. The Startup Master addon won't show any Thunderbird windows until you successfully enter your master password. Like the other weak methods, it can be circumvented by starting Thunderbird in safe mode, and your profile remains available to anyone who knows where to look for it. But it's enough to deter casual or accidental snoopers.