Java

Open a Persistent SMTP Connection

Demonstrates the Chilkat MailMan.OpenSmtpConnection method, which explicitly opens a connection to the SMTP server and authenticates if a username and password, OAuth2 token, or other applicable settings have been provided. This example opens the connection, notes where sending would occur, and closes it.

Background: By default, sending a single email opens a connection, sends, and closes it. When sending many messages, that per-message overhead adds up. Explicitly calling OpenSmtpConnection once, sending in a loop, then CloseSmtpConnection keeps a single authenticated session open for the whole batch — substantially faster and gentler on the server than reconnecting each time.

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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[])
  {
    boolean success = false;

    //  Demonstrates the MailMan.OpenSmtpConnection method, which explicitly opens a connection
    //  to the SMTP server and authenticates if credentials (or an OAuth2 token) have been
    //  provided.

    CkMailMan mailman = new CkMailMan();

    //  Configure the SMTP server connection.
    mailman.put_SmtpHost("smtp.example.com");
    mailman.put_SmtpPort(465);
    mailman.put_SmtpSsl(true);
    mailman.put_SmtpUsername("user@example.com");
    mailman.put_SmtpPassword("myPassword");

    //  Explicitly open (and authenticate) the SMTP connection.

    success = mailman.OpenSmtpConnection();
    if (success == false) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    System.out.println("SMTP connection opened.");

    //  ... send one or more emails here ...

    //  Close the connection when done.
    success = mailman.CloseSmtpConnection();
    if (success == false) {
        System.out.println(mailman.lastErrorText());
        return;
        }
  }
}