Create an RWMimeMultipart
Construct the part as an instance of
RWMimeMultipart:
RWMimeMultipart multipartMessage;
Although a multipart is not required to contain a preamble, most multipart messages that contain human-readable content provide one. Set the preamble using the setPreamble() function:
multipartBody.setPreamble("This is a MIME message.\r\n"
"\r\n"
"If you see this message, your user"
"agent is not MIME-compliant\r\n");
