[Your letterhead, if desired; if not, your return address]
[Date of letter—month, day, and year]
[Recipient's first and last names]
[Street or P.O. box address]
[City, State ZIP code]
Dear [recipient's name]:
I am writing to convey my sincere apology for mistakenly backing into your mailbox with my car yesterday. I realize that your mailbox was seriously damaged during this accident and will need to be replaced. Therefore, I plan to purchase a new mailbox for you and will either install it or will pay for a professional installation. I would like to do this as soon as possible, so please call me so that I can get the specifications on the mailbox and to discuss the details about the mailbox replacement with you.
Again, I apologize for this accident and for any inconvenience it might cause. I look forward to hearing from you soon so we can work out the mailbox replacement details.
[Sender's first and last names]