Possible Clues:

• Receiver's cutting edge?
• Dear (usually) device for getting information from correspondents out
• 'Dear Sir or Madam', perhaps?
• ''Dear Mom,'' for example (2 words)
• Dear as a knife may be?
• To whom it may concern, the start of 14 across could be used as an introduction?
• "Dear Mom," for example (2 words)
• Tool similar to a paper knife
• Makeshift weapon in a murder mystery
• Clichéd weapon in a parlor mystery