Sending attachments through a Dynamic Send Port

I spent a bit of time getting a Dynmic Send Port to email a message to a recipient as a text attachment (regardless of the filename suffix).  The following documents the properties that need to be set on the message, and corresponding send port.

1. Create the message (”msgEnvelope”) as a Multi-Part message, with the required message in the Message Body Part (”Attachment”)
2. Set the following properties of the Envelope Message:
   msgEnvelope(SMTP.Subject) = <Email Subject>;
msgEnvelope(SMTP.From) = <Sender Email>;
msgEnvelope(SMTP.SMTPHost) = <Email Host name>";
// This is the default value
msgEnvelope(SMTP.SMTPAuthenticate) = 0;
// Set the message text included in the email
msgEnvelope(SMTP.EmailBodyText) = <Text in body of email>;
// Important - This is required if the EmailBodyText is set
msgEnvelope(SMTP.EmailBodyTextCharset) = "utf-8";
// A value of '1' means include Message Body Part as email attachment
msgEnvelope(SMTP.MessagePartsAttachments) = 1;
3. Set the following properties of the Message Body Part (”Attachment”):
   // Important - Change this MIME type if not sending a Text file
msgEnvelope.Attachment(Microsoft.XLANGs.BaseTypes.ContentType) = "text/plain";
// Set the Filename of the attachment
msgEnvelope.Attachment(MIME.FileName) = <Physical name of the attachment>;

4. Set the following property on the Dynamic Send Port:
   // We set the Email Address on the Port itself
Dynamic_Send_Port(Microsoft.XLANGs.BaseTypes.Address) = <recipient email address>;


The Send Port is then configured to use a custom Send Pipeline containing a Flat File assembler for the message schema to convert the message into the flat file.