using System.Web.Mail;
using System;
public class MailSender
{
 public static bool SendEmail(
 string pGmailEmail, 
 string pGmailPassword, 
 string pTo, 
 string pSubject,
 string pBody, 
 System.Web.Mail.MailFormat pFormat,
 string pAttachmentPath)
 {
 try
 {
 System.Web.Mail.MailMessage myMail = new System.Web.Mail.MailMessage();
 myMail.Fields.Add
 ("http://schemas.microsoft.com/cdo/configuration/smtpserver",
 "smtp.gmail.com");
 myMail.Fields.Add
 ("http://schemas.microsoft.com/cdo/configuration/smtpserverport",
 "465");
 myMail.Fields.Add
 ("http://schemas.microsoft.com/cdo/configuration/sendusing",
 "2");
 //sendusing: cdoSendUsingPort, value 2, for sending the message using 
 //the network.

 //smtpauthenticate: Specifies the mechanism used when authenticating 
 //to an SMTP 
 //service over the network. Possible values are:
 //- cdoAnonymous, value 0. Do not authenticate.
 //- cdoBasic, value 1. Use basic clear-text authentication. 
 //When using this option you have to provide the user name and password 
 //through the sendusername and sendpassword fields.
 //- cdoNTLM, value 2. The current process security context is used to 
 // authenticate with the service.
 myMail.Fields.Add
 ("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate","1");
 //Use 0 for anonymous
 myMail.Fields.Add
 ("http://schemas.microsoft.com/cdo/configuration/sendusername",
 pGmailEmail);
 myMail.Fields.Add
 ("http://schemas.microsoft.com/cdo/configuration/sendpassword",
 pGmailPassword);
 myMail.Fields.Add
 ("http://schemas.microsoft.com/cdo/configuration/smtpusessl",
 "true");
 myMail.From = pGmailEmail;
 myMail.To = pTo;
 myMail.Subject = pSubject;
 myMail.BodyFormat = pFormat;
 myMail.Body = pBody;
 if (pAttachmentPath.Trim() != "")
 {
 MailAttachment MyAttachment = 
 new MailAttachment(pAttachmentPath);
 myMail.Attachments.Add(MyAttachment);
 myMail.Priority = System.Web.Mail.MailPriority.High;
 }

 System.Web.Mail.SmtpMail.SmtpServer = "smtp.gmail.com:465";
 System.Web.Mail.SmtpMail.Send(myMail);
 return true;
 }
 catch (Exception ex)
 {
 throw;
 }
}
}

EmailLib.SendEmail.SendEmail("your_gmail_id", 
                             "your_gmail_password", 
                             "to_email @ anydomain.com", 
                             "This is email subject" , 
                             "This is email body", 
                             Web.Mail.MailFormat.Text, 
                             "Physical path to your Attachment")