Cloning javax.mail.Message and Cloning javax.mail.Multipart, Java 8 - java-8

Question

I'm implementing a mail Sender, near 1'6000.000 mails (with images and PDF) in one day per month (closing month extract), the mails are about 12 products...
I need to fill a Message Scratch per product... in order to not read (per email) else per product.
I'm trying to implement cloning javax.mail.Message and javax.mail.Multipart in order to be faster.
AddContent to Multipart
public static void addContent(final Multipart multipart, String contenidoCorreo) throws Exception {
MimeBodyPart mimeBodyPart = new PreencodedMimeBodyPart("8bit");
mimeBodyPart.setText(contenidoCorreo, "iso-8859-1", "html");
multipart.addBodyPart(mimeBodyPart, 0);
}
Add Image per Bytes
public static void addImageToMultipart(final Multipart multipart, byte[] contenidoImagen, String nombreImagen) throws Exception {
MimeBodyPart imagenMimeBodyPart = new MimeBodyPart();
try {
ByteArrayDataSource byteArrayDataSource = new ByteArrayDataSource(contenidoImagen, "image/*");
imagenMimeBodyPart.setDataHandler(new DataHandler(byteArrayDataSource));
imagenMimeBodyPart.setFileName(nombreImagen);
imagenMimeBodyPart.setContentID("<" + nombreImagen + ">");
imagenMimeBodyPart.setDisposition(MimeBodyPart.INLINE);
multipart.addBodyPart(imagenMimeBodyPart);
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e.getMessage());
}
}
AddPDF per File
public static void addPDF(final Multipart multipart, String ruta, String nombre) throws Exception {
Path path = Paths.get(ruta, nombre);
if (path.toFile().exists()) {
MimeBodyPart preencodedMimeBodyPart = new PreencodedMimeBodyPart("base64");
preencodedMimeBodyPart.attachFile(path.toFile());
preencodedMimeBodyPart.setFileName(nombre);
preencodedMimeBodyPart.setHeader("Content-Type", "application/pdf");
preencodedMimeBodyPart.setDisposition(MimeBodyPart.ATTACHMENT);
multipart.addBodyPart(preencodedMimeBodyPart);
MimeBodyPart pdfMimeBodyPart = new MimeBodyPart();
}
My Cloning Message
public static Message cloneMessage(Message source) {
//Multiple and Separated Exceptions because maybe not all properties are defined in some time.
Message target = new MimeMessage(source.getSession());
try {
if (source.getFrom() != null && source.getFrom().length > 0) {
Address address = (source.getFrom()[0]);
target.setFrom(new InternetAddress(((InternetAddress) address).getAddress(), ((InternetAddress) address).getPersonal()));
}
} catch (Exception ex) {
//Handle Exception
}
try {
target.setSentDate((Date) (source.getSentDate().clone()));
} catch (MessagingException ex) {
//Handle Exception
}
try {
target.setRecipients(Message.RecipientType.TO, target.getRecipients(Message.RecipientType.TO).clone());
} catch (MessagingException ex) {
//Handle Exception
}
try {
Enumeration numerationHeaders = source.getAllHeaders();
while (numerationHeaders.hasMoreElements()) {
Header header = (Header) numerationHeaders.nextElement();
target.addHeader(header.getName(), header.getValue());
}
} catch (MessagingException ex) {
//Handle Exception
}
try {
target.setSubject(new String(source.getSubject()));
} catch (MessagingException ex) {
//Handle Exception
}
try {
target.setContent(cloneMultipart((Multipart)(source.getContent())));
} catch (Exception ex) {
//Handle Exception
}
return target;
}
Cloning Multipart
public static Multipart cloneMultipart(Multipart source) {
MimeMultipart target = new MimeMultipart();
try {
for (int i = 0; i < source.getCount(); i++) {
MimeBodyPart mimeBodyPart = (MimeBodyPart)source.getBodyPart(i);
mimeBodyPart //?????
}
} catch (MessagingException ex) {
//Handle Exception
}
return target;
}
How cloning Multipart?
some advice to clone Message?
How detect the Content (the used with addContent method) has been added?