We explain what the sender of a message is, the origin of the term and what other meanings it may have. Also, your relationship with the recipient.
What is the sender?
The word sender designates, in postal and Spanish language communications, to the person that sends a package or issues a message, that is, to the issuer or originator. This is considered the starting point of the postal delivery or the message, and it is exactly where it should be returned in case the receiver cannot receive it or the address is not correct.
That is, in fact, the literal sense of the word, since the verb send comes from Latin remittere, that is, "send something to the place where it came from" or "release from an obligation", composed of the voices re ("again and miter ("Send"). Therefore, whoever sends (the sender) a message is the only one who can release the courier from the obligation to deliver it, and that is why the site to which any shipment that does not reach its recipient must be returned.
On the other hand, the verb remit can also have the sense of "relieve" or "liberate", which can be found in other contexts and disciplines of human knowledge, as is the case of medicine: it is said that the symptoms of a disease remit, when they are alleviated or tend to disappear, or a disease remits when it "frees" the patient from his ailments. For example: "If the fever does not subside with this drug, seek professional help."
Remitent and destinatary
In the world of mail and communications, a distinction is made between sender (who sends) and recipient (who receives) to identify those involved in a postal shipment. Thus, a sender can send to one or more recipients, and these roles can always be interchanged in case there is some kind of response.
The normal thing is that the name and postal information (address, sometimes telephone) of the sender always appear on the envelope or package sent, located on the opposite side to those of the receiver or recipient. That is to say, they must go in the upper left corner of the closure or the back of the envelope or envelope, while the recipient's information must go to the front of the envelope, in the place of greater visibility.