ASP.Net MVC 5 Sending Email error: The remote certificate is invalid according to the validation procedure
<p>I have an ASP.Net MVC 5 application when I send email get bellow error:</p>

<blockquote>
  <p>The remote certificate is invalid according to the validation
  procedure.</p>
  
  <p>Description: An unhandled exception occurred during the execution of
  the   current web request. Please review the stack trace for more
  information about  the error and where it originated in the code. </p>
  
  <p>Exception Details:
  System.Security.Authentication.AuthenticationException: The remote
  certificate is invalid according to the validation procedure.</p>
  
  <p>Source Error: </p>
  
  <p>An unhandled exception was generated during the execution of the
  current web request. Information regarding the origin and location of
  the exception can be identified using the exception stack trace below.</p>
  
  <p>Stack Trace: </p>
  
  <p>[AuthenticationException: The remote certificate is invalid according
  to the validation procedure.]<br>
  System.Net.Mail.ConnectAndHandshakeAsyncResult.End(IAsyncResult
  result) +113 System.Net.Mail.SmtpClient.ConnectCallback(IAsyncResult
  result) +61</p>
  
  <p>[SmtpException: Failure sending mail.]<br>
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task) +144<br>
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task) +84   VRM5.Controllers.d__5.MoveNext() in 
  C:\Users\mehdi\Documents\Visual Studio
  2015\Projects\VRM5\VRM5\Controllers\VRsController.cs:289<br>
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task) +144 
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task) +84<br>
  System.Web.Mvc.Async.TaskAsyncActionDescriptor.EndExecute(IAsyncResult
  asyncResult) +143<br>
  System.Web.Mvc.Async.&lt;>c__DisplayClass37.b__36(IAsyncResult
  asyncResult) +23<br>
  System.Web.Mvc.Async.AsyncInvocationWithFilters.b__3d()
  +112   System.Web.Mvc.Async.&lt;>c__DisplayClass46.b__3f()
  +452  System.Web.Mvc.Async.&lt;>c__DisplayClass33.b__32(IAsyncResult asyncResult) +15<br>
  System.Web.Mvc.Async.&lt;>c__DisplayClass2b.b__1c()
  +37   System.Web.Mvc.Async.&lt;>c__DisplayClass21.b__1e(IAsyncResult
  asyncResult) +241<br>
  System.Web.Mvc.Controller.b__1d(IAsyncResult
  asyncResult, ExecuteCoreState innerState) +29<br>
  System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult
  asyncResult) +111<br>
  System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +53
  System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult
  asyncResult) +19<br>
  System.Web.Mvc.MvcHandler.b__5(IAsyncResult
  asyncResult, ProcessRequestState innerState) +51<br>
  System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult
  asyncResult) +111<br>
  System.Web.CallHandlerExecutionStep.OnAsyncHandlerCompletion(IAsyncResult
  ar) +195</p>
</blockquote>

<p>my code for sending email:</p>

<pre><code>var message = new MailMessage();
//-----Send Email------------------------------------------//
message.To.Add(new MailAddress(Q_contacts.ContactEmail));  // replace with valid value 
if(CheckAD==1)
{
    message.CC.Add(new MailAddress( mehdi@hotmail.com"));
}

message.From = new MailAddress(vR.Email);  // replace with valid value
message.Subject = "Vehicle Request -"+vR.Distination;
//message.Body = string.Format(body, model.FromName, model.FromEmail, model.Message);
message.Body = MS_1;
message.IsBodyHtml = true;

using (var smtp = new SmtpClient())
{
    var credential = new NetworkCredential
    {
        UserName = "mehdi@abc.org",  // replace with valid value
        Password = "Abc@abc123"  // replace with valid value
    };
    smtp.Credentials = credential;
    smtp.Host = "mr09.hv.abc.org";
    smtp.Port = 25;
    smtp.EnableSsl = false;
    await smtp.SendMailAsync(message);
    return RedirectToAction("Index");
}
</code></pre>