CS Ph.D@UTK，接受offer的疑问求解答

今天刚收到RA的正式文件。

To accept this appointment, please sign at the designated area below in blue ink, and return the
original letter to me at the above address.

是不是说必须打印下来，签了字，再快递寄回去，还是可以把扫描件Email过去。

求达人解答，谢谢啊！