If invited by telephone, reply by telephone, saying “I would be delighted to come to your home for dinner.” or “We both look forward to attending your party on Friday, June 14th.” Confirming the day and time is essential since you may only receive a verbal invitation. Write it down immediately so you won’t wonder later whether it was 6:30 or 7:30. Whether the invitation comes by telephone or by mail, it is stylish as well as courteous to respond with a handwritten note. A more formal reply requires centering the note and writing out all numbers, such as the day of the month and the time.