Today is the Mid-Autumn Festival. Should I send a message to my boyfriend's mother saying happy holidays? He talked to his mother yesterday, but I wasn't at work?

That depends on your relationship with your mother-in-law Out of courtesy, I think as long as you have an intersection and add WeChat or leave contact information with each other. It's normal to send a message and make a phone call to say happy holidays and exchange pleasantries. If the relationship is good, it's no problem to send a small gift, even if people are not around. If you have a bad relationship with your mother-in-law, I think. After all, there is no need to please him. Mother-in-law's obstruction will probably turn your current boyfriend into your ex-boyfriend.