The postal code system of Sao Tome and Principe is administered by its national postal operator. Postal codes, made up of digits or a mix of digits and letters, identify delivery areas to speed up mail routing. When shipping internationally, always confirm the recipient postal code against the official format for that country.

For cross-border e-commerce sellers, always verify the recipient's address and ZIP code before shipping, and check whether the destination is in a remote/outlying postal area — delivery costs can differ dramatically.