Reading Unread POP3 Email

The POP3 protocol does not provide the ability to ask the server which emails are "unread". Furthermore, a pure POP3 server does not even keep this information. Some servers, such as Exchange Server, expose both POP3 and IMAP interfaces. In these cases, information about read/unread status exists on the server, but it is only available via the IMAP protocol. Email clients such as Outlook and Thunderbird keep read/unread information on the client computer. This example demonstrates how UIDLs can be saved to track and read "unread" email.

Download Chilkat Java Library

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    //  The mailman object is used for receiving (POP3)
    //  and sending (SMTP) email.
    CkMailMan mailman = new CkMailMan();

    //  Any string argument automatically begins the 30-day trial.
    boolean success;
    success = mailman.UnlockComponent("30-day trial");
    if (success != true) {
        System.out.println("Component unlock failed");
        return;
    }

    //  Set the POP3 server's hostname
    mailman.put_MailHost("mail.chilkatsoft.com");

    //  Set the POP3 login/password.
    mailman.put_PopUsername("***");
    mailman.put_PopPassword("***");

    //  We're keeping a list of already-seen UIDLs in a text file:
    //  If this is the first time you're running this example,
    //  create an empty text file named "seenUidls.txt"
    CkStringArray saSeenUidls = new CkStringArray();
    success = saSeenUidls.LoadFromFile("seenUidls.txt");
    if (success != true) {
        System.out.println("failed to load seenUidls.txt");
        return;
    }

    //  Get the complete list of UIDLs on the mail server.
    CkStringArray saUidls;
    saUidls = mailman.GetUidls();

    if (saUidls == null ) {
        System.out.println(mailman.lastErrorText());
        return;
    }

    //  We don't have set operators (yet) on the StringArray object,
    //  so create a new string array object (it's an object, not an actual array)
    //  and add the UIDLs from saUidls that aren't already seen.
    CkStringArray saUnseenUidls = new CkStringArray();

    int i;
    int n;
    n = (int) saUidls.get_Count();
    for (i = 0; i <= n - 1; i++) {
        if (saSeenUidls.Contains(saUidls.GetString(i)) != true) {
            saUnseenUidls.Append(saUidls.GetString(i));
        }

    }

    if (saUnseenUidls.get_Count() == 0) {
        System.out.println("No unseen emails!");

        return;
    }

    //  Download in full the unseen emails:
    CkEmailBundle bundle;

    bundle = mailman.FetchMultiple(saUnseenUidls);
    if (bundle == null ) {
        System.out.println(mailman.lastErrorText());

        return;
    }

    CkEmail email;
    for (i = 0; i <= bundle.get_MessageCount() - 1; i++) {
        email = bundle.GetEmail(i);
        System.out.println(email.ck_from());
        System.out.println(email.subject());
        System.out.println("----");

    }

    //  We've seen all the emails, save saUidls to "seenUidls.txt"
    saUidls.SaveToFile("seenUidls.txt");


  }
}