Is the recipient address handwritten?
Windowless Letters, Notecards, and Giftcards
The recipient and return address for Windowless Letters, Notecards, and Giftcards are handwritten. The font use is described here:
https://help.thanks.io/handwriting-style-for-envelopes
Postcards and Windowed Letters
Postcards and Windowed Letters do not use a handwritten font.