Related Clues:
- Abbr. spotted in the mailroom
- Cover sheet abbr.
- Envelope or memo abbr., perhaps
- Mailroom abbr.
- Abbr. often before a name
- Ltr.-routing word
- Check inside?: Abbr.
- SASE, for example
- Placed inside a pkg., e.g.
- Business-envelope abbreviation
- Ltr. directive
- Abbr. before a colon
- Routing letters
- Memo abbreviation
- Abbr. on a business letter, perhaps