Well, we finally decided to switch to a locking mailbox at the bottom of the mountain rather than renting the PO box for the next year. The vagaries of how that works means that it behooves us to tell as many people as possible about the change before they send mail.
We’ve done phone calls, email, online forms, and some text messages to the appropriate organizations and people, but the rest are getting these in the mail. Fingers crossed that not much falls through the cracks!
I checked the USPS site for the parameters that qualify for postcards and verified that some legal sized cardstock I had was thick enough with our Post Mistress. I used free clip art and Photoshop to make a jpg that I inserted into a document to print on our home printer.