No, this isn't necessary or typical in therapy. Please tell us what happened- you sent a message and didn't hear back?

I'd be curious to know- does your therapist usually reply? Was this the first message? Have you two discussed whether the therapist allows between session contact?

It is not therapeutic to hurt someone on purpose, so no, that wouldn't make sense. Of course, the way to know precisely why, the only way, would be to ask. Hopefully that will be a relief. Because I can't imagine any therapist saying what would amount to: "Yes, I ignored your message to cause you pain so you'd know you could survive it and still get to come and pay to see me."