HP Deskjet 6620 Color Inkjet Printer - Manual (Page 14)

3. Slide the photo/envelope feeder forward as far as it will comfortably go.
Note: If the photo paper touches the back of the paper tray, you have pushed
the feeder in as far as it needs to go.
4. Print the photo .
Postcards
Follow these steps to use the photo/envelope feeder to print a single postcard:
1. Insert the postcard into the photo/envelope feeder with the side to be printed
on facing down.
2. Gently push the postcard into the photo/envelope feeder as far as it will go
without bending.
HP Deskjet 6600 series printer User's Guide
14