I’m not aware that Asterisk supports unsolicited NOTIFY’s. It will provide the correct URI when soliciting them.
The only possible thing you could change is to add an Asterisk extension, in the context for the endpoint, that matches the request URI in the NOTIFY. However, I rather suspect you may get a 4xx, 5xx, or 6xx status based on the content type not being supported.
You didn’t say which SIP channel driver you are using, although I’m guessing that the use of the term endpoint means it is chan_pjsip. I’m pretty certain that chan_sip doesn’t support unsolicited NOTIFY’s, but less so for chan_pjsip.
In any case, NOTIFY is a one way operation. All that the peer should care about is that it got a final status. The only reason for caring about any other status would be to lest its operator know the NOTIFY was wasted.