Sending E-mail using C#

You could use the System.Net.Mail.MailMessage class of the .NET framework.

You can find the MSDN documentation here.

Here is a simple example (code snippet):

using System.Net;
using System.Net.Mail;
using System.Net.Mime;

...
try
{

   SmtpClient mySmtpClient = new SmtpClient("my.smtp.exampleserver.net");

    // set smtp-client with basicAuthentication
    mySmtpClient.UseDefaultCredentials = false;
   System.Net.NetworkCredential basicAuthenticationInfo = new
      System.Net.NetworkCredential("username", "password");
   mySmtpClient.Credentials = basicAuthenticationInfo;

   // add from,to mailaddresses
   MailAddress from = new MailAddress("[email protected]", "TestFromName");
   MailAddress to = new MailAddress("[email protected]", "TestToName");
   MailMessage myMail = new System.Net.Mail.MailMessage(from, to);

   // add ReplyTo
   MailAddress replyTo = new MailAddress("[email protected]");
   myMail.ReplyToList.Add(replyTo);

   // set subject and encoding
   myMail.Subject = "Test message";
   myMail.SubjectEncoding = System.Text.Encoding.UTF8;

   // set body-message and encoding
   myMail.Body = "<b>Test Mail</b><br>using <b>HTML</b>.";
   myMail.BodyEncoding = System.Text.Encoding.UTF8;
   // text or html
   myMail.IsBodyHtml = true;

   mySmtpClient.Send(myMail);
}

catch (SmtpException ex)
{
  throw new ApplicationException
    ("SmtpException has occured: " + ex.Message);
}
catch (Exception ex)
{
   throw ex;
}

The best way to send bulk emails for more faster way is to use threads.I have written this console application for sending bulk emails.I have seperated the bulk email ID into two batches by creating two thread pools.

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Net.Mail;

namespace ConsoleApplication1
{
    public class SendMail 
    {
        string[] NameArray = new string[10] { "Recipient 1", 
                                              "Recipient 2",
                                              "Recipient 3",
                                              "Recipient 4", 
                                              "Recipient 5", 
                                              "Recipient 6", 
                                              "Recipient 7", 
                                              "Recipient 8",
                                              "Recipient 9",
                                              "Recipient 10"
                                            };        

        public SendMail(int i, ManualResetEvent doneEvent)
        {
            Console.WriteLine("Started sending mail process for {0} - ", NameArray[i].ToString() + " at " + System.DateTime.Now.ToString());
            Console.WriteLine("");
            SmtpClient mailClient = new SmtpClient();
            mailClient.Host = Your host name;
            mailClient.UseDefaultCredentials = true;
            mailClient.Port = Your mail server port number; // try with default port no.25

            MailMessage mailMessage = new MailMessage(FromAddress,ToAddress);//replace the address value
            mailMessage.Subject = "Testing Bulk mail application";
            mailMessage.Body = NameArray[i].ToString();
            mailMessage.IsBodyHtml = true;
            mailClient.Send(mailMessage);
            Console.WriteLine("Mail Sent succesfully for {0} - ",NameArray[i].ToString() + " at " + System.DateTime.Now.ToString());
            Console.WriteLine("");

            _doneEvent = doneEvent;
        }

        public void ThreadPoolCallback(Object threadContext)
        {
            int threadIndex = (int)threadContext;
            Console.WriteLine("Thread process completed for {0} ...",threadIndex.ToString() + "at" +  System.DateTime.Now.ToString());
            _doneEvent.Set();
        }      

        private ManualResetEvent _doneEvent;
    }


    public class Program
    {
        static int TotalMailCount, Mailcount, AddCount, Counter, i, AssignI;  
        static void Main(string[] args)
        {
            TotalMailCount = 10;
            Mailcount = TotalMailCount / 2;
            AddCount = Mailcount;
            InitiateThreads();                     

            Thread.Sleep(100000);
        }

       static void InitiateThreads()
       {
            //One event is used for sending mails for each person email id as batch
           ManualResetEvent[] doneEvents = new ManualResetEvent[Mailcount];

            // Configure and launch threads using ThreadPool:
            Console.WriteLine("Launching thread Pool tasks...");

            for (i = AssignI; i < Mailcount; i++)            
            {
                doneEvents[i] = new ManualResetEvent(false);
                SendMail SRM_mail = new SendMail(i, doneEvents[i]);
                ThreadPool.QueueUserWorkItem(SRM_mail.ThreadPoolCallback, i);
            }

            Thread.Sleep(10000);

            // Wait for all threads in pool to calculation...
            //try
            //{
            // //   WaitHandle.WaitAll(doneEvents);
            //}
            //catch(Exception e)
            //{
            //    Console.WriteLine(e.ToString());   
            //}

            Console.WriteLine("All mails are sent in this thread pool.");
            Counter = Counter+1;
            Console.WriteLine("Please wait while we check for the next thread pool queue");
            Thread.Sleep(5000);
            CheckBatchMailProcess();            
        }

        static  void CheckBatchMailProcess()
        {

            if (Counter < 2)
            {
                Mailcount = Mailcount + AddCount;
                AssignI = Mailcount - AddCount;
                Console.WriteLine("Starting the Next thread Pool");

                Thread.Sleep(5000);
                InitiateThreads();
            }

            else
            {
                Console.WriteLine("No thread pools to start - exiting the batch mail application");
                Thread.Sleep(1000);
                Environment.Exit(0);
            }
        }
    }   
}

I have defined 10 recepients in the array list for a sample.It will create two batches of emails to create two thread pools to send mails.You can pick the details from your database also.

You can use this code by copying and pasting it in a console application.(Replacing the program.cs file).Then the application is ready to use.

I hope this helps you :).

Code:

using System.Net.Mail

new SmtpClient("smtp.server.com", 25).send("[email protected]", 
                                           "[email protected]", 
                                           "subject", 
                                           "body");

Mass Emails:

SMTP servers usually have a limit on the number of connection hat can handle at once, if you try to send hundreds of emails you application may appear unresponsive.

Solutions:

• If you are building a WinForm then use a BackgroundWorker to process the queue.
• If you are using IIS SMTP server or a SMTP server that has an outbox folder then you can use SmtpClient().PickupDirectoryLocation = "c:/smtp/outboxFolder"; This will keep your system responsive.
• If you are not using a local SMTP server than you could build a system service to use Filewatcher to monitor a forlder than will then process any emails you drop in there.