sender is who sends a mail. Information about the sender (who sends the letter) must be on the back of the envelope.
The data that the sender must provide to send a correspondence are:
- Sender's name
- Type and name of address + Number + Complement (if any)
- neighborhood name
- Locality name + Federative Unit (UF) Acronym
- Country (mandatory only if sender is in foreign lands).
- Zip code
In the case of orders sent by boxes or packages other than envelopes, the sender's information must be properly identified in the most visible space on the package.
If the recipient's address is incorrect or the recipient cannot be contacted, the letter is returned to sender by the postal service.
See also:meaning of zip code.
Sender and Recipient
As said, the sender is the one who sends the letter, while the recipient is the person (natural or legal) who receive the order.
As can be seen in the image below, the space destined for the recipient (front of the envelope) must contain the information on the destination of the letter.
see the recipient meaning and learn more about the difference between sender and receiver.