Related Clues:

• Something sent with a ltr.
• Env. attachment
• Abbr. on a business envelope
• Bottom-of-env. header
• Check, perhaps: Abbr.
• Unsolicited MS., perhaps
• Routing abbr.
• Abbr. before a name in a memo
• Letter's attachment (Abbr.)
• Abbr. before a name on a memo
• SASE, for one
• Line below a business name, perhaps
• Check sent with a ltr., e.g.
• Bus. letter directive
• Mail-routing abbr.