The return address on an envelope should be placed in the upper-left corner on the front side of the envelope. It is typically positioned about 1/4 inch from the top and left edges, ensuring it is clearly visible and separate from the recipient's address. This placement allows postal services to easily identify the sender's address if the mail cannot be delivered and needs to be returned

. Additionally, the delivery address is placed in the center or slightly lower center of the envelope, parallel to the longest side, and the postage stamp goes in the upper-right corner on the front side

. While the standard and most reliable location for the return address is the upper-left corner on the front, it can sometimes be placed on the back flap of the envelope. However, this is less common and may risk misinterpretation by postal machines

. In summary:

• Return address: Upper-left corner on the front of the envelope, about 1/4 inch from edges.
• Delivery address: Centered or slightly lower center on the front.
• Postage: Upper-right corner on the front.

This format ensures proper handling and return of undeliverable mail.