basanez.leopoldo's dashboard

If I select all and delete the body of a message after selecting a default font for all out-going messages, it reverts back to variable width font instead of staying on my default. i am using the OS X version of Mozilla Thunderbird 2.0.0.23. I happen to select all and delete quite often and it gets rather tedious to have to select all and update the font every time I do so or want to send out a well-formatted email. Any assistance would be very much appreciated, thank you.