通过简单的SMTP协议，实现了邮件转发的功能。同时也可以添加附件，填写SMTP服务器，收件人，主题等信息，实现邮件的转发。-Simple SMTP protocol, to achieve the e-mail forwarding function. Can also add an attachment, fill in the SMTP server, recipient, subject and other information, to achieve e-mail forwarding