pub.mime:getEnvelopeStream

mimeData	Document MIME object from which you want to generate the MIME message. (This IData object is produced by pub.mime:createMimeData.)
index	String. Optional. Index number of the body part for which you want to generate the MIME message (if you want to generate the message from a specific body part). The first body part is index number zero.
contentID	String. Optional. Value of the Content-ID header field of the body part from which you want to generate the MIME message (if you want to generate the message from a specific body part). Note: If index is specified, contentID is ignored.
suppressHeaders	String List. Optional. Names of header fields that are to be omitted from message. You can use this option to exclude header fields that getEnvelopeStream generates by default, such as Content-Type and content-encoding.
createMultipart	String. Optional. Specifies whether a multipart message is to be created, even if mimeData contains only one body part. Set to: yes to create a multipart message (Content-Type message header is set to "multipart/mixed"). no to create a message based on the number of body parts in mimeData. This is the default. If the message contains only one body part, Content-Type is set according to the contenttype setting specified when that body part was added to mimeData. If the message contains multiple body parts, Content-Type is automatically set to "multipart/mixed."

envStream	java.io.InputStream. Conditional. The MIME message as an InputStream.
mimeMessage	javax.mail.internet.MimeMessage. Conditional. This service returns a mimeMessage instead of an envStream if any of the body parts have data greater than the threshold specified by the watt.server.mime.largeDataThreshold parameter (default 25MB).