Meizu M9 sends a short message with a yellow dot in the upper right corner. What does that mean?

Don't be nervous, the yellow dot appears because the sending is unsuccessful, and it may be the receiving problem of the other party (guess it is power off, firewall shielding, non-service area, full mailbox). Send the same content another time. Should be able to turn green successfully. Relax and smile. It's not your fault. Why bother? Thank you for your question. I wish you a happy mood, good health and all the best!