在Excel格式文件中读取学生的E-mail地址、成绩、姓名等信息，然后调用Jmail链接库函数实现学生成绩单的邮件群发.并加入了一些出错处理，如选择Excel文件时选择无效信息等给出详细的判断。

-In Excel format students read E-mail address, success, name and other information, and then call Jmail link library function of the mass-mailing transcr ipts of students. And add some error handling, such as the choice of the selection of Excel file is invalid given detailed information to judge.