In retrospect, I lived in school for more than 10 years, but I am very unfamiliar with how the school operates. For example, if you were a headmaster of a university, and your school has received a group of international students, so how do you welcome these international students?
If it were me, I would write them an email like this：
Dear international students,
welcome to our school.On behalf of the school, I extend my sincere condolences to you.I hope you can join our school as soon as possible and study hard, try to be a good cultural communicator between China and abroad.
Finally, I wish you all success in your studies.