The blue dot flashes at the receiver of Apple's mobile phone.

The blue dot on Apple's mobile phone is actually an unread SMS reminder. After clicking on the SMS application, all messages with small blue dots represent unread messages. There may be an unread email that is too old for you to find. Select Edit in the upper left corner of the message, and then select Read All to remove the blue dots on the handset of Apple. Sometimes it may just show a BUG, and the system did not cancel the unread prompt in time. It can usually be solved by restarting the phone.