gistfile1.cs

using System.IO;
using System.Net.Mail;
using System.Reflection;
using System.Text;
 
namespace Infrastructure.MailMessageExtensions
{
    public static class MailMessageExtensions
    {
        public static string ToEml(this MailMessage message)
        {
            var assembly = typeof(SmtpClient).Assembly;
            var mailWriterType = assembly.GetType("System.Net.Mail.MailWriter");
 
            using (var memoryStream = new MemoryStream())
            {
                // Get reflection info for MailWriter contructor
                var mailWriterContructor = mailWriterType.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { typeof(Stream) }, null);
 
                // Construct MailWriter object with our FileStream
                var mailWriter = mailWriterContructor.Invoke(new object[] { memoryStream });
 
                // Get reflection info for Send() method on MailMessage
                var sendMethod = typeof(MailMessage).GetMethod("Send", BindingFlags.Instance | BindingFlags.NonPublic);
 
                // Call method passing in MailWriter
                sendMethod.Invoke(message, BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { mailWriter, true, true }, null);
 
                // Finally get reflection info for Close() method on our MailWriter
                var closeMethod = mailWriter.GetType().GetMethod("Close", BindingFlags.Instance | BindingFlags.NonPublic);
 
                // Call close method
                closeMethod.Invoke(mailWriter, BindingFlags.Instance | BindingFlags.NonPublic, null, new object[] { }, null);
 
                return Encoding.ASCII.GetString(memoryStream.ToArray());
            }
        }
    }
}