SmtpClient smtpClient = new SmtpClient();
smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;//指定电子邮件发送方式
smtpClient.Host = "";//指定SMTP服务器
smtpClient.Credentials = new NetworkCredential("", "");//用户名和密码
smtpClient.EnableSsl = true;
MailAddress fromAddress = new MailAddress("fromMail", "nickName");
MailAddress toAddress = new MailAddress("toMail");
MailMessage mailMessage = new MailMessage(fromAddress, toAddress);
mailMessage.Subject = "";//主题
mailMessage.Body = "";//内容
mailMessage.BodyEncoding = Encoding.Default;//正文编码
mailMessage.IsBodyHtml = true;//设置为HTML格式
mailMessage.Priority = MailPriority.Normal;//优先级
smtpClient.SendMailAsync(mailMessage);