Dart

Send an SMTP NOOP Command

Demonstrates the Chilkat MailMan.SmtpNoop method, which sends an SMTP NOOP command to the server. NOOP does nothing except elicit a positive response, which is useful for keeping a connection alive or verifying it is still responsive. This example opens an SMTP connection, sends a NOOP, and closes.

Background: When holding an SMTP connection open across many sends (see OpenSmtpConnection), an idle stretch can cause the server to time out and drop the socket. A periodic NOOP keeps the session active and confirms the server is still responding, so the next SendEmail doesn't fail on a silently-closed connection.

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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Demonstrates the MailMan.SmtpNoop method, which sends an SMTP NOOP command to the server.
  // NOOP does nothing except elicit a positive response, useful for keeping a connection
  // alive or verifying it is still responsive.

  final mailman = CkMailMan();

  // Configure the SMTP server connection.
  mailman.smtpHost = 'smtp.example.com';
  mailman.smtpPort = 465;
  mailman.smtpSsl = true;
  mailman.smtpUsername = 'user@example.com';
  mailman.smtpPassword = 'myPassword';

  // Open the SMTP connection.

  try {
    mailman.openSmtpConnection();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Send a NOOP to keep the connection alive.
  try {
    mailman.smtpNoop();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  try {
    mailman.closeSmtpConnection();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('SMTP NOOP succeeded.');
}