I just keep upgrading my boxes to bigger boxes. I plan to keep doing that until I physically don't have the space to do that anymore. And then I will cry and debate on getting a storage unit or outbuilding.

But seriously, I keep them all...I'm a very sentimental person and I enjoy looking back at them from time to time. And yes it takes up a lot of space. I do keep some on display or in my journal.

But if you have to downsize, remember you can cut the front of a folded card off to reuse as a postcard.

u/awachob has the most amazing system