You wouldn’t start off an e-mail with “My Dear X”, or “Dearest X”, since that would be too personal for a professional email, so “To X” being more impersonal seems like it would make the letter more professional-sounding, compared to “Dear X”.
You wouldn’t start off an e-mail with “My Dear X”, or “Dearest X”, since that would be too personal for a professional email, so “To X” being more impersonal seems like it would make the letter more professional-sounding, compared to “Dear X”.
I have often used, “To whom it may concern:” in professional letters.