Can't message via VRBO?

What does this mean?

It means you have manually sent a message via channel (vrbo), and it is reflected in the communication history.

Why did it fail?

That is a standard "403" Forbidden error, which is usually transient - it's just a temporary hiccup in the connection.

If you try re-sending that message 5-10 minutes later it should go through fine unless the channel is experiencing an outage. 

Thank you Rex