If you use physical stamps for your untracked packages, only use postage purchased directly from the US Postal Service (USPS).

When you purchase discounted stamps online, there is a strong chance they are counterfeit. If you use counterfeit stamps, the USPS will discard your packages without letting you know.

If you have purchased stamps anywhere but from the USPS, do not use them to ship orders on Mana Pool. You should probably destroy them and not use them for any purpose.