javamail also extract attachments of encapsulated message Content-Type: message/rfc822

I did it by adding a new filename to the included message as an .eml file and a recursion with the included message

import java.util.*;
import javax.activation.DataHandler;
import javax.mail.*;
import javax.mail.internet.*;
import javax.mail.search.*;
import java.io.FileInputStream.*;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeBodyPart;
import javax.mail.Part;
import javax.mail.Multipart;

getAttachments(Path) ;
  //function
private  String getAttachments(path) throws
    MessagingException, IOException {
    InputStream is = new FileInputStream(path);
    MimeMessage p = new MimeMessage(null, is);

    if ( p.isMimeType("multipart/*")) {
// if (contentType.contains("multipart")) {
                    Multipart multiPart = (Multipart) p.getContent();
                    int numberOfParts = multiPart.getCount();
                    for (int partCount = 0; partCount < numberOfParts; partCount++) {
            MimeBodyPart part = (MimeBodyPart)multiPart.getBodyPart(partCount);
            String disp = part.getDisposition();

            if (disp != null && disp.equalsIgnoreCase(Part.ATTACHMENT)) {
            file_name =  part.contentType == "message/rfc822" ? "message_inclus" + partCount + ".eml" :             MimeUtility.decodeText(part.getFileName());
            exportedpath = Attachments_Folder + "/" + MailFileName + "_" + file_name; 
            part.saveFile(exportedpath);
            if ( part.contentType == "message/rfc822" ) {
            getAttachments(exportedpath) 
            }
            }
        }
    }
    is.close() 
    return 1
    }

MIME does not require every body part to have a file name. If the part doesn't have a file name and you need one, you'll have to make one up yourself.

Note also that you want to be very careful when using a file name that you get in an email message. It could be something unexpected or malicious, e.g., containing "../../../../../whatever".

• Better use org.apache.commons.mail.util.MimeMessageParser.

• MimeMessageParser has as method called hasAttachments() which returns true , if message has an attachments.

• Then loop through the all attachments and check for content-type message/rfc822 from getContentType().

• Create new MimeMessage with the DataSource InputStream

final MimeMessage message = new MimeMessage(null,attachment.getInputStream());

• Finally you have MimeMessage.

Maven Dependency:

<dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-email</artifactId>
        <version>RELEASE</version>
    </dependency>

Code Sample:

public void readEmails() throws Exception{
        // mail server connection parameters
        String host = "host";
        String user = "username";
        String pwd = "pwd";

        // connect to my pop3 inbox
        Properties properties = System.getProperties();
        Session session = Session.getDefaultInstance(properties);
        Store store = session.getStore("pop3");
        store.connect(host, user, pwd);
        Folder inbox = store.getFolder("INBOX");

        inbox.open(Folder.READ_ONLY);

        // get the list of inbox messages
        Message[] messages = inbox.getMessages();

        if (messages.length == 0) System.out.println("No messages found.");

        for (int i = 0; i < messages.length; i++) {
            // stop after listing ten messages
            if (i > 10) {
                System.exit(0);
                inbox.close(true);
                store.close();
            }
            final MimeMessageParser mimeMessageParser = new MimeMessageParser((MimeMessage) messages[i]);
            mimeMessageParser.parse();
            if (mimeMessageParser.hasAttachments()) {
                List<DataSource> attachmentList = mimeMessageParser.getAttachmentList();
                System.out.println("Number of attachments: " +attachmentList.size());
                for (DataSource attachment:attachmentList
                     ) {
                    System.out.println("Name: "+attachment.getName()+"  Content Type: "+attachment.getContentType());
                    if (attachment.getContentType().equals("message/rfc822")) {
                        final MimeMessage message = new MimeMessage(null,attachment.getInputStream());
                        System.out.println("Subject of the attached failure Mail:" + message.getSubject());

                    }
                }
            }

            System.out.println("Message " + (i + 1));
            System.out.println("From : " + messages[i].getFrom()[0]);
            System.out.println("Subject : " + messages[i].getSubject());
            System.out.println("Sent Date : " + messages[i].getSentDate());
            System.out.println();
        }

        inbox.close(true);
        store.close();
    }