转自：http://hi.baidu.com/bluesky_cn/item/8bb060ace834c53f020a4df2
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：
1 using System.Net.Mail; 2 using System.Text; 3 using System.Net;
程序代码：
1 MailMessage myMail = new MailMessage(); //创建邮件实例对象 2 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 3 4 myMail.To.Add(new MailAddress("")); //接收者 5 myMail.Subject = "C#发送Email"; //邮件标题 6 myMail.SubjectEncoding = Encoding.UTF8; //标题编码 7 myMail.Body = "this is a test email!"; //邮件内容 8 myMail.BodyEncoding = Encoding.UTF8; //邮件内容编码 9 myMail.IsBodyHtml = true; //邮件内容是否支持html 10 SmtpClient smtp = new SmtpClient(); //创建smtp实例对象 11 smtp.Host = "mail.sina.com"; //邮件服务器SMTP 12 smtp.Port = 25; //邮件服务器端口 13 smtp.Credentials = new NetworkCredential("", "123456"); //邮件服务器验证信息 14 smtp.Send(myMail); //发送邮件
使用Gmail邮箱发送邮件示例
1 MailMessage myMail = new MailMessage(); 2 myMail.From = new MailAddress(""); 3 myMail.To.Add(new MailAddress("")); 4 myMail.Subject = "C#发送Email"; 5 myMail.SubjectEncoding = Encoding.UTF8; 6 myMail.Body = "this is a test email from gmail!<a href=‘http://www.sina.com.cn‘>sina</a>"; 7 myMail.BodyEncoding = Encoding.UTF8; 8 myMail.IsBodyHtml = true; 9 SmtpClient smtp = new SmtpClient(); 10 smtp.Host = "smtp.gmail.com"; 11 smtp.Port = 587; //Gmail的smtp端口 12 smtp.Credentials = new NetworkCredential("", "123456"); 13 smtp.EnableSsl = true; //Gmail要求SSL连接 14 smtp.DeliveryMethod = SmtpDeliveryMethod.Network; //Gmail的发送方式是通过网络的方式，需要指定 15 smtp.Send(myMail);
使用QQ邮箱发送邮件示例
1 MailMessage myMail = new MailMessage(); 2 myMail.From = new MailAddress(""); 3 myMail.To.Add(new MailAddress("")); 4 myMail.Subject = "C#发送Email"; 5 myMail.SubjectEncoding = Encoding.UTF8; 6 myMail.Body = "this is a test email from QQ!"; 7 myMail.BodyEncoding = Encoding.UTF8; 8 myMail.IsBodyHtml = true; 9 SmtpClient smtp = new SmtpClient(); 10 smtp.Host = "smtp.qq.com"; 11 smtp.Credentials = new NetworkCredential("", "123456"); 12 smtp.Send(myMail);