Related Clues:
- Letters before an intended recipient's name
- Subj. line alert
- Routing aid: Abbr
- Bottom-of-letter abbr
- Routing abbr. on an envelope
- SASE, perhaps: Abbr
- For whom the memo is intended: Abbr
- Letters before a name on a letter
- Ltr. in an envelope
- Envelope ltrs
- FYI kin
- ''Britannica,'' for one: Abbr
- Mail-routing letters
- Letter-routing notation
- Letter-routing abbr