People who send something, like a letter or a package.
Senders are usually helpful because they are giving something to someone else.
Examples:
The senders of the package put a lot of stamps on it.
The senders of the letter wrote their names on the back.
Senders are important because they help things get to where they need to go.
The senders of the gift made sure it was wrapped nicely.
The senders of the message wanted to make someone happy.
The senders of the email were very kind.