Why do I send a short message to others, and others can receive it, but it shows that it has not been sent?

Hello! May be these reasons, I hope I can help you, please adopt, thank you!

1. Look at your mobile phone first.

2. If the other party stops or shuts down for a long time, the transmission may also be unsuccessful.

3. If not, it may be that the other party put you on the information blacklist.