I received a Christmas card in the mail, but on the envelope they intentionally misgendered me. I'm going to tear it up even though I know it has family pictures inside it.
This sounds like a difficult situation for you, but what makes you think destroying a card would be a good idea?
Because I want people to stop misgendering me!
Tearing up the card wouldn't let anyone know you're upset and would be far too passive aggressive if your goal is to prevent this from happening again. You need to let the people you care about know that they've upset you, because getting revenge is juvenile and serves to only hurt you.
No, they've been calling me a boy for the past three years, and I'm going to make sure it never happens again by tearing up this card.
Instead of doing destroying the Christmas card, I think you should talk with your family. Let them know that they are really upsetting and hurting you when they refer to you by the wrong gender. Having a discussion with them is more likely to have a positive outcome than seeking revenge on them.