The message was sent out and rejected by the other party. Can the other party see it?

You can't. When the message is rejected by the other party, the other party has added it to the blacklist and set the message rejection function. In this case, the sent message will not be transmitted to the other party's device, and the other party will not be able to see the sent message.

The other party cannot receive its messages and phone calls for other reasons. The best way to determine whether the other party blacklists itself is to communicate directly with the other party.