Parameter Count Mismatch

O boy!.... Today, I bang my head to solve this issue....

I was trying to Send an attachment email through Dot Net Amazon SDK. But, got stuck with this issue.. Since the following code is standard, that you can get from internet, to convert the MailMessage To MemoryStream. Finally identify the issue and solved.

public static MemoryStream ConvertMailMessageToMemoryStream(MailMessage message)
        {
            Assembly assembly = typeof(SmtpClient).Assembly;
            Type mailWriterType = assembly.GetType("System.Net.Mail.MailWriter");
            MemoryStream fileStream = new MemoryStream();
            ConstructorInfo mailWriterContructor = mailWriterType.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { typeof(Stream) }, null);
            object mailWriter = mailWriterContructor.Invoke(new object[] { fileStream });
            MethodInfo sendMethod = typeof(MailMessage).GetMethod("Send", BindingFlags.Instance | BindingFlags.NonPublic);
            sendMethod.Invoke(message, BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { mailWriter, true}, null); // Throws Error , Parameter Count Mismatch
            MethodInfo closeMethod = mailWriter.GetType().GetMethod("Close", BindingFlags.Instance | BindingFlags.NonPublic);
            closeMethod.Invoke(mailWriter, BindingFlags.Instance | BindingFlags.NonPublic, null, new object[] { }, null);
            return fileStream;
        }


You have to change the parameter array object. Since "Send" Private method has three parameters System.Net.Mail.MailMessage.Send(BaseWriter writer, bool sendEnvelope, bool allowUnicode).

Correct Code


public static MemoryStream ConvertMailMessageToMemoryStream(MailMessage message)
        {
            Assembly assembly = typeof(SmtpClient).Assembly;
            Type mailWriterType = assembly.GetType("System.Net.Mail.MailWriter");
            MemoryStream fileStream = new MemoryStream();
            ConstructorInfo mailWriterContructor = mailWriterType.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { typeof(Stream) }, null);
            object mailWriter = mailWriterContructor.Invoke(new object[] { fileStream });
            MethodInfo sendMethod = typeof(MailMessage).GetMethod("Send", BindingFlags.Instance | BindingFlags.NonPublic);
            sendMethod.Invoke(message, BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { mailWriter, true, true}, null); // Success
            MethodInfo closeMethod = mailWriter.GetType().GetMethod("Close", BindingFlags.Instance | BindingFlags.NonPublic);
            closeMethod.Invoke(mailWriter, BindingFlags.Instance | BindingFlags.NonPublic, null, new object[] { }, null);
            return fileStream;
        }