If you're filing outside US, here are few things you need to keep an eye on.
Payment: You may pay fees with bank drafts, cashier’s checks, certified checks, personal checks, and money orders that are drawn on U.S. financial institutions and payable in U.S. funds. See details at here.
Mailing Address: USCIS mails you the notification letter, RFE letter or other letters via USPS. We strongly suggest using a US address to receive USCIS mail, as USCIS typically does not send mail internationally. You may not receive USCIS mail if you use a non-US address.
Submit single-sided, standard 8½ x 11 letter-size pages.
Note: If you cannot find US bank payment solutions or a US mailing address, contact our customer service. We provide US payment and mailing solutions to ease your petition process.