How to send mail asynchronously in asp.net with MailMessage

With Microsoft.NET Framework 2.0 everything is asynchronous and we can send mail also asynchronously. This features is very useful when you send lots of bulk mails like offers , Discounts , Greetings . You don’t have to wait for response from mail server and you can do other task .

By using    SmtpClient.SendAsync Method (MailMessage, Object)   you need to do 

System.Net.Mail has also added asynchronous support for sending email. To send asynchronously, you need need to

1. Wire up a SendCompleted event
2. Create the SendCompleted event
3. Call SmtpClient.SendAsync

smtpClient.send() will initiate the sending on the main/ui  thread and would block. 

smtpClient.SendAsync() will pick a thread from the .NET Thread Pool and execute the method on that thread. So your main UI will not hang or block .

Let's create a simple example to send mail. For sending mail asynchronously you need to create a event handler that will notify that mail successfully sent or some errors occurred during sending mail. Let’s create a mail object and then we will send it asynchronously. You will require System.Net.Mail space to import in your page to send mail.

/you require following name space
using System.Net.Mail;

//creating mail message object
MailMessage mailMessage = new MailMessage();
mailMessage.From = new MailAddress("Put From mail address here");
mailMessage.To.Add(new MailAddress("Put To Email Address here"));
mailMessage.CC.Add(new MailAddress("Put CC Email Address here"));
mailMessage.Bcc.Add(new MailAddress("Put BCC Email Address here"));
mailMessage.Subject = "Put Email Subject here";
mailMessage.Body = "Put Email Body here ";
mailMessage.IsBodyHtml = true;//to send mail in html or not

SmtpClient smtpClient = new SmtpClient("Put smtp server host here", 25);//portno here
smtpClient.EnableSsl = false; //True or False depends on SSL Require or not
smtpClient.UseDefaultCredentials = true ; //true or false depends on you want to default credentials or not
Object mailState = mailMessage;

//this code adds event handler to notify that mail is sent or not
smtpClient.SendCompleted += new SendCompletedEventHandler(smtpClient_SendCompleted);
try
{
 smtpClient.SendAsync(mailMessage, mailState);
}
catch (Exception ex)
{
 Response.Write(ex.Message);
 Response.Write(ex.StackTrace);
}

void smtpClient_SendCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
{
MailMessage mailMessage = e.UserState as MailMessage;
if (!e.Cancelled && e.Error != null)
{
     Response.Write("Email sent successfully");
}
else
{
     Response.Write(e.Error.Message);
     Response.Write(e.Error.StackTrace);
}
}