He'd leave little notes on my desk sometimes, saying 'Stick with school,' or sometimes he'd send a postcard from his business trips saying the same thing.
Instead, he settled for a postcard to her and one to her son, each with a bland "Having a great time" message.
Write about your experience in that location and mail the postcard to yourself.
These are the oldest type of postcard and were made before July 1, 1898.
This can simply be included in the wording along with your phone number or email address or it can be included as a stamped RSVP postcard that your guests can simply drop in the mail to let you know they're coming.