United States Citizenship and Immigration Services (USCIS) can communicate with people overseas through email and USPS Priority Mail with Delivery Confirmation. For example, USCIS sends an email notification within 24 hours of accepting an application or petition to overseas customers. USCIS also uses the Secure Mail Initiative (SMI) to deliver certain immigration documents, such as Green Cards, travel documents, and employment authorization documents, using USPS Priority Mail with Delivery Confirmation. This allows USCIS to confirm delivery of these documents.