What should you do if a close friend sends you a message saying that you want to get married?

Look at friendship, sincerity and economic ability.

Generally speaking, it is impolite to send mass marriage news itself, and there is no signature or invitation. If your friendship is average and there is nothing in your life and work, you don't have to get a gift. Respect is mutual. But if the relationship is good and you want to continue, you can wait for his official notice before replying to him.