NIP-17 はそもそも受信側が対応クライアントで専用リレーをセットアップしていないと送信しない仕様になっていますね

> Clients SHOULD publish kind 14 events to the 10050-listed relays. If that is not found that indicates the user is not ready to receive messages under this NIP and clients shouldn't try.

https://github.com/nostr-protocol/nips/blob/master/17.md#publishing