Related Clues:

• Cover sheet abbr
• Directed to: Abbr
• E-mail subject-line abbr
• Letter abbr
• Mailing label abbr
• "One more thing," for short
• Env. router
• Afterthought introducer
• "To whom it actually does concern" letters
• 'As an aside,' in chat lingo
• "It's for you," on an env
• Letters before an intended recipient's name
• 'Incidentally,' in a text
• Subj. line alert
• Routing aid: Abbr