Related Clues:

• A check, one might hope: Abbr.
• Multi-vol. set
• Address abbr.
• Abbr. at the bottom of a business letter
• Direct mail abbr.
• S.A.S.E., e.g.
• Went around
• Env. contents
• Business letter abbr.
• Env. notation
• Abbr. on some letter headings
• Letter abbr.
• Ref. work
• Bottom-of-letter abbr.
• Letters in a letter