The meaning of a transmitted message in communication is a

The meaning of a transmitted message is a collaborative activity between sender and receiver.

Meaning is jointly built as the receiver interprets what the sender encodes.

Calling it a sender activity alone ignores the receiver's share in making meaning.

Calling it a receiver activity alone ignores the sender's role in shaping it.

Naming it a channel activity mistakes the carrier for the meaning it conveys.

Because both parties construct the sense together, the act is collaborative.