The SMS shows that it has been delivered. Is it because the other party is not black?

It doesn't necessarily show that the other party is not black.

The delivery of the short message only shows that the short message has been successfully sent to the other party's mobile phone, and it is not certain whether the other party has received and read the short message. Even if the other party blacked it out, the short message may still show that it has been sent, but this message will not enter the other party's inbox, but will be temporarily stored in the blacklist mailbox or interception record of the mobile phone, and generally will not remind the owner.

Therefore, you can't judge whether the other party has blacked yourself out just because the SMS has been sent.