save System.Net.mail.MailMessage as .msg file

Question

I am building an application where i am obligated to create a MailMessage (System.Net.mail.MailMessage) and save it on the disk as .msg extention not .eml

Below is the method i'm using to save a MailMessage as .msg file:

   public static void Save(MailMessage Message, string FileName)
    {
        Assembly assembly = typeof(SmtpClient).Assembly;
        Type _mailWriterType =
          assembly.GetType("System.Net.Mail.MailWriter");

        using (FileStream _fileStream =
               new FileStream(FileName, FileMode.Create))
        {
            // Get reflection info for MailWriter contructor
            ConstructorInfo _mailWriterContructor =
                _mailWriterType.GetConstructor(
                    BindingFlags.Instance | BindingFlags.NonPublic,
                    null,
                    new Type[] { typeof(Stream) },
                    null);

            // Construct MailWriter object with our FileStream
            object _mailWriter =
              _mailWriterContructor.Invoke(new object[] { _fileStream });

            // Get reflection info for Send() method on MailMessage
            MethodInfo _sendMethod =
                typeof(MailMessage).GetMethod(
                    "Send",
                    BindingFlags.Instance | BindingFlags.NonPublic);

            // Call method passing in MailWriter
            _sendMethod.Invoke(
                Message,
                BindingFlags.Instance | BindingFlags.NonPublic,
                null,
                new object[] { _mailWriter, true },
                null);

            // Finally get reflection info for Close() method on our MailWriter
            MethodInfo _closeMethod =
                _mailWriter.GetType().GetMethod(
                    "Close",
                    BindingFlags.Instance | BindingFlags.NonPublic);

            // Call close method
            _closeMethod.Invoke(
                _mailWriter,
                BindingFlags.Instance | BindingFlags.NonPublic,
                null,
                new object[] { },
                null);
        }
    }

But the saved msg file doesn't open and below is the error: "Cannot open file xyz.msg.The file file may not exist, you may not have permission to open it or it may be open by another program...."

My question is: How to save System.Net.mail.MailMessage as msg file?

Answer 1

Here Ryan suggests an easy and great way to do it whithout any effort.

You can actually configure the SmtpClient to send emails to the file system instead of the network. You can do this programmatically using the following code:

SmtpClient client = new SmtpClient("mysmtphost");
client.DeliveryMethod = SmtpDeliveryMethod.SpecifiedPickupDirectory;
client.PickupDirectoryLocation = @"C:\somedirectory";
client.Send(message);

You can also set this up in your application configuration file like this:

 <configuration>
     <system.net>
         <mailSettings>
             <smtp deliveryMethod="SpecifiedPickupDirectory">
                 <specifiedPickupDirectory pickupDirectoryLocation="C:\somedirectory" />
             </smtp>
         </mailSettings>
     </system.net>
 </configuration>

Answer 2

If you are referring to Outlook MSG file format check the MSG format specification published by Microsoft. Following answer to similar question might also help.