Send email with Unity

Hi. I am using Unity 5.6.1f1 and I want ot send an email from unity on the Click of a button, I do not have any email form to be filled in, the message body and Subject are aall hard coded. I am unable toi send the email. I have tried several times, also changed player settings APi to 2.0. I get the error IOException Connection closed when I use Send(mail)n method, but with SendAsync I dont get that message but the email is not sent to the recepient email. this is my script which I have attached to an ampty game object and then assigned that game object to a a button in the scene and selected the function name of the script for the Onclick event of the button.I get the message "Sending Email..."in my console but no email is sent.

         public void SendMail()
 {


     MailMessage mail = new MailMessage();

     mail.From = new MailAddress("sender@gmail.com");
     mail.To.Add("receiver@mtc.edu.om");
     mail.Subject = "Test Mail";
     mail.Body = "This is for testing SMTP mail from gmail";

     SmtpClient smtpServer = new SmtpClient("smtp.gmail.com");
     smtpServer.Port = 465;

     smtpServer.Credentials = new System.Net.NetworkCredential("sender@gmail.com", "senderpassword") as ICredentialsByHost;
     smtpServer.DeliveryMethod = SmtpDeliveryMethod.Network;
     smtpServer.EnableSsl = true;
     ServicePointManager.ServerCertificateValidationCallback =
       delegate (object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
       { return true; };
     smtpServer.SendCompleted += new SendCompletedEventHandler(MailDeliveryComplete);
     smtpServer.Send(mail);
     Debug.Log("success");
 }

 static void MailDeliveryComplete(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
 {
     Console.Write("Message \"{0}\".", e.UserState);

     if (e.Error != null)
         Console.WriteLine("Error sending email.");
     else if (e.Cancelled)
         Console.WriteLine("Sending of email cancelled.");
     else
         Console.WriteLine("Message sent.");
 }
 }

If I use port 587 Unity freezes. I have tried the SMTP server and port for yahoo mail also, and get the same error. Please help.