Austin Parker
123, X Street, Y Avenue
Manhattan, NY-10009
(123) 456-7890
[Subject: Normally bold, summarizes the intention of the letter] -Optional-
Dear Austin Parker,
I really apologise that you did not receive the package as expected. We have been getting very huge orders, and it has been a tough time to service them with equal priority every time, and therefore the delay occurred. To reduce such instances, we have started roping in new staff. I apologise again for the inconveniences it might have caused you, and look forward to your continued patronage.
Sincerely,
Abhi