Question

So, the below code used to work in .NET 4 to get a System.Net.Mail.MailMessage object as a MemoryStream, however with the release of .NET 4.5 beta a runtime exception occurs.

Assembly assembly = typeof(SmtpClient).Assembly;
Type mailWriterType = assembly.GetType("System.Net.Mail.MailWriter");
using (MemoryStream stream = new MemoryStream())
{
    ConstructorInfo mailWriterContructor = mailWriterType.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { typeof(Stream) }, null);
    object mailWriter = mailWriterContructor.Invoke(new object[] { stream });
    MethodInfo sendMethod = typeof(MailMessage).GetMethod("Send", BindingFlags.Instance | BindingFlags.NonPublic);
    sendMethod.Invoke(message, BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { mailWriter, true }, null);

    .....
}

Runtime exception occurs on sendMethod.Invoke().

Answer 1

Managed to figure out how to get this working again in .NET 4.5 beta. The private API Send() method in MailMessage has changed to: internal void Send(BaseWriter writer, bool sendEnvelope, bool allowUnicode)

Please find updated code below.

Assembly assembly = typeof(SmtpClient).Assembly;
Type mailWriterType = assembly.GetType("System.Net.Mail.MailWriter");
using (MemoryStream stream = new MemoryStream())
{
    ConstructorInfo mailWriterContructor = mailWriterType.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { typeof(Stream) }, null);
    object mailWriter = mailWriterContructor.Invoke(new object[] { stream });
    MethodInfo sendMethod = typeof(MailMessage).GetMethod("Send", BindingFlags.Instance | BindingFlags.NonPublic);
    sendMethod.Invoke(message, BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { mailWriter, true, true }, null);

    .....
}