Can I use an international address for my return address? 

Pre-sort (presorted) mail requires a valid U.S return address by the USPS, particularly for commercial, marketing or bulk mailings.  A U.S. return address is mandatory when using precanceled stamps, company permit imprints, etc.  If you are an international company using Thanks.io services please use our default PO Box as your return address.  The address can be found in the account section where you would normally add your mailing address.  Just click on the highlighted “thanks.io’s PO Box” and it will pre-fill the address for you.