下面用到的邮件账号和密码都不是真实的，需要测试就换成自己的邮件账号。需要引用：using System.Net.Mail;using System.Text;using System.Net;程序代码：        MailMessage myMail = new MailMessage(); //创建邮件实例对象        myMail.From = new MailAddress(""); //发送者，要和邮件服务器的验证信息对应，不能随便更改               myMail.To.Add(new MailAddress("")); //接收者        myMail.Subject = "C#发送Email"; //邮件标题        myMail.SubjectEncoding = Encoding.UTF8; //标题编码        myMail.Body = "this is a test email!"; //邮件内容        myMail.BodyEncoding = Encoding.UTF8; //邮件内容编码        myMail.IsBodyHtml = true;     //邮件内容是否支持html        SmtpClient smtp = new SmtpClient(); //创建smtp实例对象        smtp.Host = "mail.sina.com"; //邮件服务器SMTP        smtp.Port = 25;                  //邮件服务器端口        smtp.Credentials = new NetworkCredential("", "123456"); //邮件服务器验证信息        smtp.Send(myMail); //发送邮件使用Gmail邮箱发送邮件示例        MailMessage myMail = new MailMessage();        myMail.From = new MailAddress("");        myMail.To.Add(new MailAddress(""));        myMail.Subject = "C#发送Email";        myMail.SubjectEncoding = Encoding.UTF8;        myMail.Body = "this is a test email from gmail!<a href=http://www.mamicode.com/‘http://www.sina.com.cn‘>sina";        myMail.BodyEncoding = Encoding.UTF8;        myMail.IsBodyHtml = true;        SmtpClient smtp = new SmtpClient();        smtp.Host = "smtp.gmail.com";        smtp.Port = 587; //Gmail的smtp端口        smtp.Credentials = new NetworkCredential("", "123456");        smtp.EnableSsl = true; //Gmail要求SSL连接        smtp.DeliveryMethod = SmtpDeliveryMethod.Network; //Gmail的发送方式是通过网络的方式，需要指定        smtp.Send(myMail);使用QQ邮箱发送邮件示例        MailMessage myMail = new MailMessage();        myMail.From = new MailAddress("");        myMail.To.Add(new MailAddress(""));        myMail.Subject = "C#发送Email";        myMail.SubjectEncoding = Encoding.UTF8;        myMail.Body = "this is a test email from QQ!";        myMail.BodyEncoding = Encoding.UTF8;        myMail.IsBodyHtml = true;        SmtpClient smtp = new SmtpClient();        smtp.Host = "smtp.qq.com";        smtp.Credentials = new NetworkCredential("", "123456");        smtp.Send(myMail);