Historical clue formulations

• Letter opener — 2025-07-20
• With 40-Across, open for business? — 2025-01-15
• It may follow a name and address — 2008-11-13
• Formal introduction — 2007-01-27
• Formal introduction? — 2005-04-15
• Generic greeting — 1997-02-15
• Letter opener — 1994-07-09