Send Email with Multiple Threads(Mass Mail) in C#

In previous section, I introduced how to use asynchronous mode. In this section, I will introduce how to send mass emails with multiple threads in C#.

Introduction

Based on asynchronous mode, you can create multiple SmtpClient instances in your application and send email in multiple threads. Here is a simple sample demonstrates how to use asynchronous mode to send email in multiple threads.

Note

Remarks: All of samples in this section are based on first section: Send email in a simple C# project. To compile and run the following example codes successfully, please click here to learn how to create the test project and add reference of EASendMail to your project.

[C# - Send Mass Emails with Multiple Threads - Example]

The following example codes demonstrate how to send mass email with multiple threads in C#.

Note

To get the full sample projects, please refer to Samples section.

using System;
using System.Collections.Generic;
using System.Text;
using EASendMail; //add EASendMail namespace
namespace mysendemail
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] arRcpt = new string[]{"test1@adminsystem.com",
                "test2@adminsystem.com",
                "test3@adminsystem.com" };

            int nRcpt = arRcpt.Length;
            SmtpMail[] arMail = new SmtpMail[nRcpt];
            SmtpClient[] arSmtp = new SmtpClient[nRcpt];
            SmtpClientAsyncResult[] arResult = new SmtpClientAsyncResult[nRcpt];
            for (int i = 0; i < nRcpt; i++)
            {
                arMail[i] = new SmtpMail("TryIt");
                arSmtp[i] = new SmtpClient();
            }

            for (int i = 0; i < nRcpt; i++)
            {
                SmtpMail oMail = arMail[i];
                // Set sender email address
                oMail.From = "sender@emailarchitect.net";

                // Set recipient email address
                oMail.To = arRcpt[i];

                // Set email subject
                oMail.Subject = "mass email test from c#";

                // Set email body
                oMail.TextBody = "test from c#, this email is sent to " + arRcpt[i];
                // Your smtp server address
                SmtpServer oServer = new SmtpServer("smtp.emailarchitect.net");

                // User and password for ESMTP authentication, if your server doesn't require
                // User authentication, please remove the following codes.
                oServer.User = "test@emailarchitect.net";
                oServer.Password = "testpassword";

                // If your smtp server requires SSL connection, please add this line
                // oServer.ConnectType = SmtpConnectType.ConnectSSLAuto;
                SmtpClient oSmtp = arSmtp[i];

                // Submit email to BeginSendMail method and return
                // to process another email
                arResult[i] = oSmtp.BeginSendMail(oServer, oMail, null, null );
                Console.WriteLine( String.Format( "Start to send email to {0} ...",
                    arRcpt[i] ));
            }
            // All emails were sent by BeginSendMail Method
            // now get result by EndSendMail method
            int nSent = 0;
            while (nSent < nRcpt)
            {
                for (int i = 0; i < nRcpt; i++)
                {
                    // this email has been sent
                    if (arResult[i] == null)
                        continue;
                    // wait for specified email ...
                    if (!arResult[i].AsyncWaitHandle.WaitOne(10, false))
                    {
                        continue;
                    }
                    try
                    {
                        // this email is finished, using EndSendMail to get result
                        arSmtp[i].EndSendMail(arResult[i]);
                        Console.WriteLine(String.Format("Send email to {0} successfully",
                            arRcpt[i]));
                    }
                    catch (Exception ep)
                    {
                        Console.WriteLine(
                           String.Format("Failed to send email to {0} with error {1}: ",
                           arRcpt[i], ep.Message));
                    }
                    // Set this email result to null, then it won't be processed again
                    arResult[i] = null;
                    nSent++;
                }
            }
        }
    }
}

Next Section

At next section I will introduce how to send email using EASendMail Service Queue in ASP.NET/C#.

Appendix

Comments

If you have any comments or questions about above example codes, please click here to add your comments.