Can Xiao Xie, the son-in-law, say thank you by SMS?

Of course. Kouxie is a very respectful and modest expression, which is used to express gratitude to elders or superiors, and sometimes to apologize to each other or express sincere apologies. When writing Xiao Xie's short message, you should pay attention to the proper wording, sincerity and sensibility, express your true feelings and gratitude, let the other party feel your sincerity and sincerity, and achieve the effect of emotional communication.