[Friday, March 14th]
Several readers have reported an issue in which Mail.app only prints message headers, leaving message body text out. The problem appears to manifest more often when the "Command P" keyboard combination is used to print documents.
As such, some users have had success with opening messages in their own windows (by double-clicking them in the mail browser) then using the Print button at the top of the window.
Other users have been able to alleviate this problem by delete then re-adding printers and/or resetting the printing system. Open Printer Setup Utility, located in Applications/Utilities and look at the "Printer List" Highlight and delete all entries. Alternatively, go to the "Printer Setup Utility" menu at the top of the screen and select "Reset Printing System". Click the "Add" button and re-add your printer(s).
If you are experiencing a similar issue, please let us know.