i found it depended on the clerk you get at the p.o. one let them all go at 44 cents, and another insisted on 64 cents. they arrived at my house with every am't you could imagine, and none were refused, and none were sent back to me. my first boom i was told by one person that they had to pay a dime, or something, but she chose to p.i.f. no big deal. i don't think anyone sends it out with too little postage on purpose. go to your p.o. and find out how much they want. the yellow clasp envelopes cost me 64cents, white envelopes 44 cents. that's all i know. good luck!