456, X Street, Y Avenue,
[Subject: Normally bold, summarizes the intention of the letter] -Optional-
Dear Jack Martinez,
Something has come up and I won’t be able to help you decorate for the 8th grade social on Friday afternoon.
I’d like to swing by your house Tuesday or Wednesday to bring the balloons and streamers I purchased. Let me know if you’ll be home on those days.
Kelly will still be attending the social so I will send refreshments with her.