Okay, if you are sending magnets, maybe you can learn from my idiocy. DON'T DROP THEM IN A BLUE MAILBOX!!!! I live in the city so this is primarily how I send my mail. I had already weighed one and stamped them, so I figured, why not? Because they are magnets...and the mailbox is metal...ha. One stuck right to the drop door, but of course only after I had dropped in about 15. I'm confident they are now plastered to the walls of the mailbox, never again to see the light of day. And of course I don't know which ones I dropped in...