1234, West 67 Street,
Carlisle, MA 01741,
[Subject: Normally bold, summarizes the intention of the letter] -Optional-
Dear Austin Parker,,
I regret to inform you that I cannot meet you for dinner this Monday. This is because I need to finish a project by Monday noon and I will not be able to make it to lunch. Please arrange a meeting on Tuesday or Wednesday. I will be highly obliged.