(Java) POP3: Download Most Recent Email (method 2)

How to ready the N most recent email from a POP3 server.

The POP3 protocol does not provide the ability to request the most recent email, nor does it provide the ability to download email based on read/unread status or any other criteria. The design principle behind POP3 is that it is a temporary holding store for incoming email and email clients or other applications will transfer email from the POP3 server to a local persistent store where it will be managed. Therefore, POP3 does not provide sophisticated functionality (as opposed to IMAP which has the opposite design philosophy: that email is maintained and organized on the server).

This example shows one possible way to retrieve the N most recent emails from a POP3 server. It downloads the complete list of UIDLs and then downloads the last N into a bundle object. It assumes that the UIDLs will be returned by the POP3 server ordered by date such that the 1st email in the UIDL list is the oldest, and the last email is the newest.

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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[])
  {
    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // The mailman object is used for receiving (POP3) 
    // and sending (SMTP) email.
    CkMailMan mailman = new CkMailMan();
    boolean success;

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

    // Set the POP3 login/password.
    mailman.put_PopUsername("admin@chilkatsoft.com");
    mailman.put_PopPassword("****");

    // Get the complete list of UIDLs
    CkStringArray saUidls = mailman.GetUidls();
    if (mailman.get_LastMethodSuccess() == false) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    // Get the 10 most recent UIDLs
    // The 1st email is the oldest, the last email is the newest
    // (usually)
    int n;
    int startIdx;
    n = saUidls.get_Count();
    if (n > 10) {
        startIdx = n - 10;
        }
    else {
        startIdx = 0;
        }

    int i = 0;
    CkStringArray saUidls2 = new CkStringArray();
    if (n > 0) {
        for (i = startIdx; i <= n - 1; i++) {
            success = saUidls2.Append(saUidls.getString(i));
            }

        }

    // Download in full the 10 most recent emails:
    CkEmailBundle bundle = mailman.FetchMultiple(saUidls2);
    if (mailman.get_LastMethodSuccess() == false) {
        System.out.println(mailman.lastErrorText());
        return;
        }

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

        i = i+1;
        }
  }
}