One should infer from this that messages need not be verbal or written. The non-verbal signs, like smiles, frowning of the face, shrugs, gesticulations, etc., that accompany spoken words often add more meaning to the words themselves. One might still be transmitting some messages without writing anything or speaking a word.
The principal or educational planner who just walks into the office without speaking a word or acknowledging greetings is sending a message. The administrator who shuts his/ her door as soon as s/he comes to the office is sending a message. A clean office with structures in good shape is also sending a message.
There are both interpersonal and intrapersonal messages. When a message involves more than one person it is interpersonal communication. In Intrapersonal message it is possible for one to think aloud or correct what one has written.