If it is blacked out, will it show that it has been sent?

Whether to send after power failure depends on the software used, as follows:

Tik Tok: If Tik Tok is hacked by others, the user will display "Sending Failed" when sending a message, prompting that "TA cannot receive your message due to the privacy settings of the other party", and the receiver cannot receive the message.

Wechat: If Wechat is hacked, the user will receive "Message sent, but rejected by the other party" when sending a message, and it will not show that it has been sent.

SMS: If the SMS is hacked by others, the user will not display any content when sending the SMS, and the SMS content will be blacklisted automatically by the hacker's mobile phone system without SMS reminder.