Related Clues:
- Fax cover sheet abbr
- Routing notation
- Envelope-routing abbreviation
- Abbr. on some emails
- Address label abbr
- "To" on a memo
- Email subject line abbr
- Mail routing letters
- Start of many a chain email
- Start of some email subj. lines
- Abbr. before a colon and a name
- Name preceder on some envs
- Letters on an envelope addressed to a company
- Letters facilitating sorting
- Letter heading abbr