How To send Email with C# on Unity 3D 4.1.2?

first I came across this article:

Dave On C# Programming tutorials

I got few errors and I start searching:

Unity 3 - Sending Email with C#

but I just cannot figure out how to solve this:

 using UnityEngine;
 using System.Net;
 using System.Net.Mail;
 using System.Collections;
 
 public class SendEmail : MonoBehaviour {
     void Start () {
         Debug.Log("asdgf");
         SendEmailF();
         
     }
     private void SendEmailF(){
         // Create a System.Net.Mail.MailMessage object
         MailMessage message = new MailMessage();
         
         // Add a recipient
         message.To.Add("Reciver.Email@gmail.com");
         
         // Add a message subject
         message.Subject = "Test Email Subject message";
         
         // Add a message body
         message.Body = "Test email Body message.";
         
         // Create a System.Net.Mail.MailAddress object and 
         // set the sender email address and display name.
         message.From = new MailAddress("Sender.Email@gmail.com", "John Smith");
         
         // Create a System.Net.Mail.SmtpClient object
         // and set the SMTP host and port number
         SmtpClient smtp = new SmtpClient("smtp.gmail.com", 587);
         
         // If your server requires authentication add the below code
         // =========================================================
         // Enable Secure Socket Layer (SSL) for connection encryption
         smtp.EnableSsl = true;
         
         // Do not send the DefaultCredentials with requests
         smtp.UseDefaultCredentials = false;
         
         // Create a System.Net.NetworkCredential object and set
         // the username and password required by your SMTP account

1.try

 //        smtp.Credentials = new NetworkCredential("Sender.Email@gmail.com", "Password");
                 // Assets/SendEmail.cs(43,22): error CS0266: Cannot implicitly convert type `System.Net.NetworkCredential' to `System.Net.ICredentialsByHost'. An explicit conversion exists (are you missing a cast?)

2.try

 //        smtp.Credentials = (ICredentialsByHost) new NetworkCredential("Sender.Email@gmail.com", "Password");
                 // wow no error but when I run the code:
                 // InvalidOperationException: SSL authentication error: RemoteCertificateNotAvailable, RemoteCertificateChainErrors
                 // System.Net.Mail.SmtpClient.<callback>m__4 (System.Object sender, System.Security.Cryptography.X509Certificates.X509Certificate certificate, System.Security.Cryptography.X509Certificates.X509Chain chain, SslPolicyErrors sslPolicyErrors)
                 // System.Net.Security.SslStream+<BeginAuthenticateAsClient>c__AnonStorey7.<>m__A (System.Security.Cryptography.X509Certificates.X509Certificate cert, System.Int32[] certErrors)
                 // Mono.Security.Protocol.Tls.SslClientStream.OnRemoteCertificateValidation (System.Security.Cryptography.X509Certificates.X509Certificate certificate, System.Int32[] errors)
                 // Mono.Security.Protocol.Tls.SslStreamBase.RaiseRemoteCertificateValidation (System.Security.Cryptography.X509Certificates.X509Certificate certificate, System.Int32[] errors)
                 // Mono.Security.Protocol.Tls.SslClientStream.RaiseServerCertificateValidation (System.Security.Cryptography.X509Certificates.X509Certificate certificate, System.Int32[] certificateErrors)
                 // Mono.Security.Protocol.Tls.Handshake.Client.TlsServerCertificate.validateCertificates (Mono.Security.X509.X509CertificateCollection certificates)
                 // Mono.Security.Protocol.Tls.Handshake.Client.TlsServerCertificate.ProcessAsTls1 ()
                 // Mono.Security.Protocol.Tls.Handshake.HandshakeMessage.Process ()
                 // (wrapper remoting-invoke-with-check) Mono.Security.Protocol.Tls.Handshake.HandshakeMessage:Process ()
                 // Mono.Security.Protocol.Tls.ClientRecordProtocol.ProcessHandshakeMessage (Mono.Security.Protocol.Tls.TlsStream handMsg)
                 // Mono.Security.Protocol.Tls.RecordProtocol.InternalReceiveRecordCallback (IAsyncResult asyncResult)
                 // Rethrow as IOException: The authentication or decryption has failed.
                 // Mono.Security.Protocol.Tls.SslStreamBase.AsyncHandshakeCallback (IAsyncResult asyncResult)
                 // Rethrow as SmtpException: Message could not be sent.
                 // System.Net.Mail.SmtpClient.Send (System.Net.Mail.MailMessage message)
                 // SendEmail.SendEmailF () (at Assets/SendEmail.cs:59)
                 // SendEmail.Start () (at Assets/SendEmail.cs:9)

3.try

 //        NetworkCredential myCred = new NetworkCredential("Sender.Email@gmail.com","Password");
 //        
 //        CredentialCache myCache = new CredentialCache();
 //        
 //        myCache.Add(new Uri("www.contoso.com"), "Basic", myCred);
 //        
 //        WebRequest wr = WebRequest.Create("www.contoso.com");
 //        smtp.Credentials = myCache;
                 // Assets/SendEmail.cs(69,33): error CS0246: The type or namespace name `Uri' could not be found. Are you missing a using directive or an assembly reference?
                 // Assets/SendEmail.cs(69,25): error CS1502: The best overloaded method match for `System.Net.CredentialCache.Add(System.Uri, string, System.Net.NetworkCredential)' has some invalid arguments
                 // Assets/SendEmail.cs(69,25): error CS1503: Argument `#1' cannot convert `object' expression to type `System.Uri'

the rest of the code

         // =========================================================
         
         // Send the message
         smtp.Send(message);
     }
 }

it's all in 1 BIG script but I only uncomment a line after 1,2,3 try and get an error that's commented

I made it like this to look a little bit more organized

and I'm using Unity 3D 4.1.2