Possible Clues:

• FYI medium
• ''Didn't you get the ___?''
• Note doctor put next to case of medicine
• Some random e-mail that's returned?
• 'I guess you missed the ___'
• Exec's message holder
• Note that might start 'Re:'
• Note turned up concealed by welcome mat
• ___ pad (place for notes)
• Short written message