public static void sendEmail(string toAddress, string emailbody)
{
var fromAddress = ConfigurationManager.AppSettings["EmailAddress"];
string fromPassword = ConfigurationManager.AppSettings["EmailPassword"].ToString();
const string subject = "Job Recommendation";


var smtp = new SmtpClient
{
Host = ConfigurationManager.AppSettings["SmtpServer"].ToString(),
Port = int.Parse(ConfigurationManager.AppSettings["SmtpPort"]),
EnableSsl = true,
DeliveryMethod = SmtpDeliveryMethod.Network,
UseDefaultCredentials = false,
Credentials = new NetworkCredential(fromAddress, fromPassword)
};
using (var message = new MailMessage(fromAddress, toAddress, subject, HttpUtility.HtmlEncode(emailbody)))
{
smtp.Send(message);
}
}

add key="EmailAddress" value="**********@gmail.com"/>//Email Address
add key="EmailPassword" value="*********"/> //Emial PWD
add key="SmtpServer" value="smtp.gmail.com"/>
add key="SmtpPort" value="587"/>

--带附件版本->

var fromAddress = "allenyinj@gmail.com";
string fromPassword = "yj1989120";
const string subject = "CV";


var smtp = new SmtpClient
{
Host = "smtp.gmail.com",
Port = 587,
EnableSsl = true,
DeliveryMethod = SmtpDeliveryMethod.Network,
UseDefaultCredentials = false,
Credentials = new NetworkCredential(fromAddress, fromPassword)
};
MailMessage email=new MailMessage(fromAddress, "allen.yin.jun@gmail.com");
email.Subject = "INLINE attachment TEST";
email.IsBodyHtml = true;
string attachmentPath = "C:\\3.jpeg";
Attachment inline = new Attachment(attachmentPath);
inline.ContentDisposition.Inline = true;
inline.ContentDisposition.DispositionType = DispositionTypeNames.Inline;
//inline.ContentId = "1";
//inline.ContentType.MediaType = "image/png";
inline.ContentType.Name = Path.GetFileName(attachmentPath);
email.Attachments.Add(inline);
email.Body = "test";
smtp.Send(email);

email.Dispose();

//如果没有路径，用Stream

Attachment letter = new Attachment(FileUploadLetter.FileContent, FileUploadLetter.PostedFile.ContentType);
letter.ContentDisposition.Inline = true;
letter.ContentDisposition.DispositionType = DispositionTypeNames.Inline;
//inline.ContentId = "1";
letter.ContentType.MediaType = FileUploadLetter.PostedFile.ContentType;
letter.ContentType.Name = Path.GetFileName(FileUploadLetter.PostedFile.FileName);
letter.Name = Path.GetFileName(FileUploadLetter.PostedFile.FileName);

//如果希望通过匿名邮件发送 则

var smtp = new SmtpClient
{
Host = "serverName",
Port = 25, //匿名发送端口
EnableSsl = false,
DeliveryMethod = SmtpDeliveryMethod.Network,
UseDefaultCredentials = false,
//Credentials = new NetworkCredential(fromAddress, fromPassword)
};