[Your letterhead, if desired; if not, your return address]

[Date of letter-month, day, and year]

[Recipient's first and last names]
[Company name]
[Street or P.O. box address]
[City, State ZIP code]

Dear [recipient's name]:

Can you believe it's already been 20 years since we graduated from Hills High School? We want to catch up with you and other classmates and find out what's been happening in your life over all these years. So please mark your calendar for the weekend of June 15th through the 17th, when we will hold our 20th Hills reunion in downtown Chicago.

We are making the reunion plans and will be in touch with you soon with all the details. We hope you can make it to the reunion. It'll be great to see you and reminisce on high school days!

Best regards,

[Signature]

[Sender's first and last names]