Java view,download,filter email using javax.mail

Java SDK doesn't come with inbuilt mail API but Java-EE (now called Jakarta EE) provides several utility library like json, servlet, web-service, jms, validation, xml, regexp including email.

In this example I'm going to show how we can connect to email server (eg: gmail) and download/view seen/unseen emails.

Required Dependency :jakarta.mail

Add this dependency with latest version in your pom.xml or manually download/add the jar file to your project's lib.

<dependency>
    <groupId>com.sun.mail</groupId>
    <artifactId>jakarta.mail</artifactId>
</dependency>

The API Usage:

Ideally, the steps would be as following:

- Create Session with host, protocal type etc

- Get message store (Store) for the email protocol. The supported protocols are IMAP, POP, SMTP etc

- Connect to the host using username/password

- Open folder and search for messages

The API Usage with code example:

- Create Session with host, protocol type etc

Properties properties = new Properties();
properties.put("mail.imap.host", host);
properties.put("mail.store.protocol", protocal);
Session emailSession = Session.getDefaultInstance(properties);

 - Get message store (Store) for the email protocol. The supported protocols are IMAP, POP, SMTP etc

Store store = emailSession.getStore(protocal);

- Connect to the host using username/password

store.connect(host, user, password);

- Open folder and search for messages

Folder emailFolder = store.getFolder("INBOX");
emailFolder.open(Folder.READ_ONLY);

Search using filters

Flags seen = new Flags(Flags.Flag.SEEN);
FlagTerm unseenFlagTerm = new FlagTerm(seen, false);
Message[] messages = emailFolder.search(unseenFlagTerm);

Complete Example:

import javax.mail.*;
import javax.mail.search.FlagTerm;
import java.util.Properties;

public class MailllllIMAP {

    public static void check(String host, String protocal, String user, String password) {
        try {
            Properties properties = new Properties();
            properties.put("mail.imap.host", host);
            properties.put("mail.store.protocol", protocal);
            Session emailSession = Session.getDefaultInstance(properties);

            Store store = emailSession.getStore(storeType);
            store.connect(host, user, password);
            Folder emailFolder = store.getFolder("INBOX");
            emailFolder.open(Folder.READ_ONLY);

            //unseen email filter
            Flags seen = new Flags(Flags.Flag.SEEN);
            FlagTerm unseenFlagTerm = new FlagTerm(seen, false);
            Message[] messages = emailFolder.search(unseenFlagTerm);

            System.out.println("Total messages: " + messages.length);

            for (Message m : messages) {
                System.out.println(("From: " + m.getFrom()[0]));
                System.out.println(("Subject: " + m.getSubject()));
                System.out.println(("Subject: " + m.getContent()));
                //other fields
            }


            //close or do more stuff
            emailFolder.close(false);
            store.close();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {

        String host = "pop.gmail.com";
        String protocal = "imaps";
        String username = "XXXX@gmail.com";
        String password = "XXXXXXX";

        check(host, protocal, username, password);

    }

}

What if you get an error like this?

    AuthenticationFailedException: [AUTH] Username and password not accepted.

You get this error when trying to gmail. You will need to turn ON the "Allow less secure apps" option on https://www.google.com/settings/security/lesssecureapps