说明：  利用smtp方式发送电子邮件,在窗体中填好发件人的地址和收件人的地址,和要发送的内容,然后点击send就可以发送邮件了
(use smtp sending e-mail, which completed Form in the sender's address and the address of the addressee, to be sent and the content, then it can send the mail)