I noticed this yesterday when looking up what model ink cartridges I needed to order. HP will send postage-paid envelopes for ink cartridges to be recycled. I ordered several which should last a while and hopefully will get then in a few days.
They don’t advertise it too well, but it’s not a bad program. So if you have a HP printer send them back. Boxes are available for businesses who go through a lot of ink.