Sender (noun)

A person or device that sends a message, package, or signal.

Origin:

Late middle english: from send + -er.

Examples:

1. The sender of the letter included a return address and asked for a reply.
2. The sender of the email attached some files and requested feedback.
3. The sender of the package marked it with a delivery address and a due date.
4. The sender of the signal transmitted it over a long distance and waited for a response.
5. The sender of the message encrypted it and used a secure channel to ensure privacy.