When the SMS is signed, the system will automatically detect it. If it does not meet the requirements, it will prompt that the SMS signature is illegal.
In order to prevent illegal information from appearing in signature information, when users set and send signatures, the system will automatically filter illegal words, and unqualified signatures will not be allowed to set and send. Either because X is not entered, or the content after X is empty, or the content is too long (more than 48 words).