Will the recipient who sends SF Express receive a short message prompting the express number?

This is not necessarily a friend. They should receive it, because it is stipulated in their service specification, but it is not implemented to the letter. When they are busy, they often forget it. If they think about it once in a while, they will send you short messages according to the requirements of that day, so it gives people the impression that it is irregular, irregular and hard to say.