Related Clues:

• Wd. component
• Monogram pt.
• Return env.
• U.S.P.S. delivery
• Response facilitator: Abbr.
• Encl. for a reply
• Brief correspondence?
• It may be used for many unhappy returns: Abbr.
• Ed.'s request, often
• Word unit: Abbr.
• A, B, or C: abbr.
• USPS unit
• RSVP card enclosure
• Env. filler
• USPS piece