Emailer.cs

//  Emailer.cs
//  http://www.mrventures.net/all-tutorials/sending-emails
using System.Collections;
using System.Net;
using System.Net.Mail;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
using UnityEngine;

public class Emailer : MonoBehaviour {
    [SerializeField] TMPro.TextMeshProUGUI txtData;
    [SerializeField] UnityEngine.UI.Button btnSubmit;
    [SerializeField] bool sendDirect;

    const string kSenderEmailAddress = "CoderBoy6000@gmail.com";
    const string kSenderPassword = "CoderBoy6000!!!";
    const string kReceiverEmailAddress = "CoderBoy6000@gmail.com";

    // Method 2: Server request
    const string url = "https://coderboy6000.000webhostapp.com/emailer.php";

    void Start() {
        UnityEngine.Assertions.Assert.IsNotNull( txtData );
        UnityEngine.Assertions.Assert.IsNotNull( btnSubmit );
        btnSubmit.onClick.AddListener( delegate {
            if ( sendDirect ) {
                SendAnEmail( txtData.text );
            }
            else {
                SendServerRequestForEmail( txtData.text );
            }
        } );
    }

    // Method 1: Direct message
    private static void SendAnEmail( string message ) {
        // Create mail
        MailMessage mail = new MailMessage();
        mail.From = new MailAddress( kSenderEmailAddress );
        mail.To.Add( kReceiverEmailAddress );
        mail.Subject = "Email Title";
        mail.Body = message;

        // Setup server 
        SmtpClient smtpServer = new SmtpClient("smtp.gmail.com");
        smtpServer.Port = 587;
        smtpServer.Credentials = new NetworkCredential(
            kSenderEmailAddress, kSenderPassword ) as ICredentialsByHost;
        smtpServer.EnableSsl = true;
        ServicePointManager.ServerCertificateValidationCallback =
            delegate ( object s, X509Certificate certificate,
            X509Chain chain, SslPolicyErrors sslPolicyErrors ) {
                Debug.Log( "Email success!" );
                return true;
            };

        // Send mail to server, print results
        try {
            smtpServer.Send( mail );
        }
        catch ( System.Exception e ) {
            Debug.Log( "Email error: " + e.Message );
        }
        finally {
            Debug.Log( "Email sent!" );
        }
    }

    // Method 2: Server request
    private void SendServerRequestForEmail( string message ) {
        StartCoroutine( SendMailRequestToServer( message ) );
    }

    // Method 2: Server request
    static IEnumerator SendMailRequestToServer( string message ) {
        // Setup form responses
        WWWForm form = new WWWForm();
        form.AddField( "name", "It's me!" );
        form.AddField( "fromEmail", kSenderEmailAddress );
        form.AddField( "toEmail", kReceiverEmailAddress );
        form.AddField( "message", message );

        // Submit form to our server, then wait
        WWW www = new WWW(url, form);
        Debug.Log( "Email sent!" );

        yield return www;

        // Print results
        if ( www.error == null ) {
            Debug.Log( "WWW Success!: " + www.text );
        }
        else {
            Debug.Log( "WWW Error: " + www.error );
        }
    }
}