Change email contents display font size of Thunderbird

Thunderbird email contents display appears to act similarly to a web brower, so hitting Ctrl and the '-'/'+' signs shrinks/enlarges the font size.

Note: this is not explained anywhere, and the preferences all change a different setting, AFAIK

Nicer settings for cssh: terminal_font, terminal_size, terminal_args

.clusterssh/config

1. terminal_font=5x8
2. terminal_size=140x48
3. terminal_args=-fg green
4. auto_close=1