From an interview with David Shipley and Will Schwalbe authors of Send:The Essential Guide to Email for Office and Home as published in Allure Magazine 9/07: Excerpts:
Mind your manners: Try to start off with a salutation and end with a sign-off like best or regards.
Stick to the subject: Always give your messages a clear, compelling subject line -- and keep it short. Attachments should always be clearly labeled and under one megabyte.
Keep up appearances: Stick to Times New Roman or Arial -- in black, no colors or background.
