Basically all their addresses are stored in DH's emails and every year we go through this painful process of trying to find them in time for Christmas cards.
Generally we reserve cards for close friends and family, less than 20. This year I went to a lot of effort to make beautiful (expensive) cards of 1 yo DS printed. They arrived, I addressed mine and suggested we do his. DH couldn't be bothered to look the addresses up, he wanted to play computer games. I've suggested a couple more time since and he's batted me off. I'm fed up with trying now. He has major issues with procrastinating, that I think will only be solved by me not bailing him out.
AIBU to just leave and let his family not get Christmas cards? It will be noticed. But I'm already badgering him about more important things, I don't want to care about this anymore. The only thing that irks me is the pile of beautiful unused cards that won't be good for anything after Christmas (given DS age and the Merry Christmas message they can't be reused.)