Accessed from Configure 
Preferences Quick Text
Originally intended to insert pre-composed snippets of text into messages, this has become more of a "Quick Document", allowing the insertion into a message body of formatted text, by holding the ALT key and pressing the number keys 1 to 9. This can be very useful in speeding up your work.
There is no limit to the amount of text you may enter here, and it can be formatted for use in HTML format messages. NOTE that all formatting will be lost in plain-text messages.