MailMessage objMail = new MailMessage();

objMail.Subject = "邮件主题";

objMail.Body = "邮件正文";

string mfrom = txtFrom.Value; //从页面读取发送者地址

objMail.From = new MailAddress(mfrom);

string mt = txtTo.Value; //从页面读取接收者地址

MailAddress ma = new MailAddress(mt);

objMail.To.Add(ma);

objMail.IsBodyHtml = true;//指示邮件为html格式的值

objMail.Priority = MailPriority.High;//设置邮件的优先级

objMail.Attachments.Add(new Attachment("F:aba.doc"));//添加附件

SmtpClient smtp = new SmtpClient();

smtp.Host = "……"//smtp事务的IP地址，如smtp.cc.com

smtp.Send(objMail);//发送邮件