What is the smallest mailing size?

Is there a smallest size envelope you can mail? Ugh, tell me about it! The post office…don’t even get me started. I once made this super cute, tiny little card, all decorated and everything, for my friend’s birthday. And guess what? They wouldn't take it! It was too small. Apparently, the absolute smallest size you can mail is 3.5 inches by 5 inches. Like, seriously? What’s the big deal with something a little smaller, you know? My tiny card was perfectly fine, just a little…compact. It felt so arbitrary! I swear, sometimes it feels like they make these rules just to mess with us. It's so annoying when you’re trying to be creative and then bam, regulations. It's like, where’s the room for a little…artistic license, huh? It's 3.5 x 5 or nothing, apparently. So remember that, folks. Learn from my tiny-card tragedy!