I turned off my phone and turned it back on, but my iMessage is still not working.

Does your iPhone have problems sending text messages to one other recipient, or to all other recipients?

Which iPhone model, and which iOS version?

Is this iPhone new, or new to you? Or is this an iPhone you’ve been using to send messages for a while?

And is this involving a Mac as indicated by your footer, or an iPhone?

I’m not yet certain the following applies to this case, but here is what Apple recommends for activating iMessage itself:

If you get an error when trying to activate iMessage or FaceTime - Apple Support

Apple iMessage messages don’t go to email.

Text messages (SMS messages) might, but that’s determined by your carrier and not your iPhone.

Could you describe what you’re encountering here in a little more detail?