Java

Get the POP3 UIDL of an Email

Demonstrates the read-only Chilkat Email.Uidl property, which contains the unique message identifier assigned by a POP3 server; the value is also represented by the X-UIDL header field. This example sets X-UIDL directly to illustrate how it maps to the Uidl property (normally the value comes from the POP3 server during download).

Background: A UIDL ("unique ID listing") is POP3's stable identifier for a message in a mailbox — it stays the same across sessions, so a client can remember which messages it has already downloaded and avoid fetching them again. Note this is POP3-specific: IMAP uses its own UID instead, which Chilkat stores in the ckx-imap-uid header rather than in Uidl.

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Java

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[])
  {
    //  Demonstrates the read-only Email.Uidl property, which contains the unique message
    //  identifier assigned by a POP3 server.  The value is represented by the X-UIDL header
    //  field.  Here we set X-UIDL directly to show how it maps to the Uidl property.

    CkEmail email = new CkEmail();

    //  Normally the POP3 server assigns this; we set it here for demonstration.
    email.AddHeaderField("X-UIDL","0000000123abcdef");

    System.out.println("Uidl = " + email.uidl());
  }
}