public static void CreateMessageInlineAttachment3(string server, string
textMessage)
{
    // Create a message and set up the recipients.
    MailMessage message = new MailMessage(
       "[email protected]",
       "[email protected]",
       "An inline text message for you.",
       "Message: ");

    // Attach the message string to this email message.
    Attachment data = new Attachment(textMessage, MediaTypeNames.Text.Plain);
    // Send textMessage as part of the email body.
    message.Attachments.Add(data);
    ContentDisposition disposition = data.ContentDisposition;
    disposition.DispositionType = DispositionTypeNames.Inline;
    //Send the message.
    // Include credentials if the server requires them.
    SmtpClient client = new SmtpClient(server);
    client.Credentials = (ICredentialsByHost)CredentialCache.DefaultNetworkCredentials;
    client.Send(message);
    data.Dispose();
}