When addressing an envelope, the sender's name and address should be placed in the top left-hand corner of the envelope. The recipient's name and mailing address should be written in the lower center portion of the envelope.
If the envelope is not addressed properly, it will likely be returned to the sender or sent to a dead-letter file if there is no return address.
If using a standard postage stamp, it should be placed in the top right corner. Otherwise, the post office has to meter and stamp the envelope, and the postal clerk places either a printed postage sticker or a stamp in that area.