The definition of language is (according to Google), human communication.
For there to be communication, you need a recipient. Which means that mere written words have no meaning without someone reading and interpreting them.
You can analyze syntax and structure all you want, but meaning depends on people's interpretations, which are subjective and depend on multiple other factors.
For instance, if I'm angry, I'll read a text message or an email and interpret it in a completely different way than if I'm calm. The meaning I interpret will also depend on who sent me the message. Neither of these things are captured in the syntax of the messages.