To do one even better do what we do when sending cards out, I was told by our postmaster if we did not want our card to go in to a sorting machine all we had to do is write DO NOT BEND in black mark on the left hand lower corner so they can see it and it goes in to what they call a pre shorted bin also writing it on the back of the envelope, Doing all this is easy and you can use penny sleeves and top loader and they will make it to anyone just fine and safe we had zero issues.
also do not forget to wrap them in paper after putting them in a top loader and we also use team bags as well with one card in a top loader and the rest if more then one in a penny sleeve.....that is it :) From Terra