You can’t control what others do, because at the end of the day she’ll probably keep sending them but you getting so angry is only affecting you really. It’s like drinking poison and expecting the other person to feel it. She’s 2, she isn’t gonna have a clue what cards say anyway.
If it comes in the mail, then instead of opening it next time, just put return to sender and send it back.
The only thing that you can control is your reaction. People will always annoy you but you can stop letting it bother you. Just laugh it off as your daughter doesn't know anything about this so it doesn't affect her in the slightest.