Error while placing order. Error 1: The remote server returned an error: (404) Not Found.

Hi,

Nop V: 3,50

Payment confirm page not work _!


Error :

The log entry message.Short message:  Error while placing order. Error 1: The remote server returned an error: (404) Not Found.

Originating page of exception.Page URL:  https://www.example.com/realonepagecheckout/confirmorder
The referrer URL.Referrer URL:  /realonepagecheckout
Date/Time the log entry was created.Created on:  7/30/2015 1:47:22 PM

/**/

Error
The log entry message.Short message:  The remote server returned an error: (404) Not Found.
The details for the log entry.Full message:  System.Net.WebException: The remote server returned an error: (404) Not Found. at System.Net.HttpWebRequest.GetResponse() at Nop.Services.Messages.WorkflowMessageService.SendOrderPlacedCustomerNotification(Order order, Int32 languageId, String attachmentFilePath, String attachmentFileName) at Nop.Services.Orders.OrderProcessingService.PlaceOrder(ProcessPaymentRequest processPaymentRequest)

Looks to me like the site isn't set up correctly to send emails out and is failing when the notification email is being sent

Thank you for your attention

The site sends mail, I have done the essential controls. But it doesn't direct to confirm page when payment is completed by credit card or money transfer and it shows this warning on the screen. But actually it has had the payment by credit card.