Dear Sir/Madam,
I'm delighted you have accepted our invitation to speak at the conferencein [city] on [date].
As we agreed, you'll be speaking on the topic rdially invited to attend thecelebration at [hotel], [location], on [date] from [time] to [time].
[name] has been the President of [company] since [year]. During thisperiod, [company] expanded its business greatly. Now it's our opportunity tothank him for his years of exemplary leadership and wish him well for a happyretirement. Please join us in saying good-bye to [name].
See you on [date].
Yours sincerely
[name]
[title