diff --git a/lib/Cron/CronHelper.php b/lib/Cron/CronHelper.php
index 5672a034f7..f886ebeb5a 100644
--- a/lib/Cron/CronHelper.php
+++ b/lib/Cron/CronHelper.php
@@ -60,6 +60,7 @@ class CronHelper {
       QueueEndpoint::ACTION_RUN,
       $data
     );
+    $url = str_replace(home_url(), self::getSiteUrl(), $url);
     $args = array(
       'blocking' => false,
       'sslverify' => false,
@@ -70,20 +71,21 @@ class CronHelper {
     return wp_remote_retrieve_body($result);
   }
 
-  private static function getSiteUrl() {
-    // additional check for some sites running on a virtual machine or behind
+  static function getSiteUrl($site_url = false) {
+    // additional check for some sites running inside a virtual machine or behind
     // proxy where there could be different ports (e.g., host:8080 => guest:80)
-
-    // if the site URL does not contain a port, return the URL
-    if(!preg_match('!^https?://.*?:\d+!', site_url())) return site_url();
-    preg_match('!://(?P<host>.*?):(?P<port>\d+)!', site_url(), $server);
-    // connect to the URL with port
-    $fp = @fsockopen($server['host'], $server['port'], $errno, $errstr, 1);
-    if($fp) return site_url();
-    // connect to the URL without port
-    $fp = @fsockopen($server['host'], $server['port'], $errno, $errstr, 1);
-    if($fp) return preg_replace('!(?=:\d+):\d+!', '$1', site_url());
-    // throw an error if all connection attempts failed
+    $site_url = ($site_url) ? $site_url : home_url();
+    $parsed_url = parse_url($site_url);
+    // 1. if the site URL does not contain a port, return the URL
+    if(empty($parsed_url['port'])) return $site_url;
+    // 2. connect to the URL with specified port
+    $fp = @fsockopen($parsed_url['host'], $parsed_url['port'], $errno, $errstr, 1);
+    if($fp) return $site_url;
+    $port = (strtolower($parsed_url['scheme']) === 'http') ? 80 : 443;
+    // 3. connect to the URL with default port
+    $fp = @fsockopen($parsed_url['host'], $port, $errno, $errstr, 1);
+    if($fp) return sprintf('%s://%s', $parsed_url['scheme'], $parsed_url['host']);
+    // 4. throw an error if all connection attempts failed
     throw new \Exception(__('Site URL is unreachable.'));
   }
 
diff --git a/tests/unit/Cron/CronHelperTest.php b/tests/unit/Cron/CronHelperTest.php
new file mode 100644
index 0000000000..d2cba2b587
--- /dev/null
+++ b/tests/unit/Cron/CronHelperTest.php
@@ -0,0 +1,121 @@
+<?php
+
+use MailPoet\API\Endpoints\Cron;
+use MailPoet\Cron\CronHelper;
+use MailPoet\Cron\Daemon;
+use MailPoet\Models\Setting;
+
+class CronHelperTest extends MailPoetTest {
+  function testItDefinesConstants() {
+    expect(CronHelper::DAEMON_EXECUTION_LIMIT)->equals(20);
+    expect(CronHelper::DAEMON_EXECUTION_TIMEOUT)->equals(35);
+    expect(CronHelper::DAEMON_REQUEST_TIMEOUT)->equals(2);
+    expect(CronHelper::DAEMON_SETTING)->equals('cron_daemon');
+  }
+
+  function testItCanCreateDaemon() {
+    $token = 'create_token';
+    $time = time();
+    CronHelper::createDaemon($token);
+    $daemon = Setting::getValue(CronHelper::DAEMON_SETTING);
+    expect($daemon)->equals(
+      array(
+        'status' => Daemon::STATUS_STARTING,
+        'token' => $token,
+        'updated_at' => $time
+      )
+    );
+  }
+
+  function testItCanRestartDaemon() {
+    $token = 'restart_token';
+    $time = time();
+    CronHelper::restartDaemon($token);
+    $daemon = Setting::getValue(CronHelper::DAEMON_SETTING);
+    expect($daemon)->equals(
+      array(
+        'status' => Daemon::STATUS_STARTING,
+        'token' => $token,
+        'updated_at' => $time
+      )
+    );
+  }
+
+  function testItLoadDaemon() {
+    $daemon = array(
+      'status' => 'created',
+      'token' => 'some_token',
+      'updated_at' => '12345678'
+    );
+    Setting::setValue(
+      CronHelper::DAEMON_SETTING,
+      $daemon
+    );
+    expect(CronHelper::getDaemon())->equals($daemon);
+  }
+
+  function testItCanSaveDaemon() {
+    // when saving daemon, 'updated_at' value should change
+    $daemon = array(
+      'status' => 'created',
+      'token' => 'some_token',
+      'updated_at' => '12345678'
+    );
+    Setting::setValue(
+      CronHelper::DAEMON_SETTING,
+      $daemon
+    );
+    $time = time();
+    CronHelper::saveDaemon($daemon);
+    $daemon['updated_at'] = $time;
+    expect(CronHelper::getDaemon())->equals($daemon);
+  }
+
+  function testItCanCreateRandomToken() {
+    // random token is a string of 5 characters
+    $token1 =  CronHelper::createToken();
+    $token2 =  CronHelper::createToken();
+    expect($token1)->notEquals($token2);
+    expect(is_string($token1))->true();
+    expect(strlen($token1))->equals(5);
+  }
+
+  function testItCanGetSiteUrl() {
+    // 1. do nothing when the url does not contain port
+    $site_url = 'http://example.com';
+    expect(CronHelper::getSiteUrl($site_url))->equals($site_url);
+
+    if(getenv('WP_TEST_ENABLE_NETWORK_TESTS') !== 'true') return;
+
+    //2. when url contains valid port, try connecting to it
+    $site_url = 'http://example.com:80';
+    expect(CronHelper::getSiteUrl($site_url))->equals($site_url);
+    //3. when url contains invalid port, try connecting to it. when connection fails,
+    // another attempt will be made to connect to the standard port derived form URL schema
+    $site_url = 'http://example.com:8080';
+    expect(CronHelper::getSiteUrl($site_url))->equals('http://example.com');
+    //4. when connection can't be established, exception should be thrown
+    $site_url = 'https://invalid:80';
+    try {
+      CronHelper::getSiteUrl($site_url);
+      self::fail('Site URL is unreachable exception not thrown.');
+    } catch(Exception $e) {
+      expect($e->getMessage())->equals('Site URL is unreachable.');
+    }
+  }
+
+  function testItCanEnforceExecutionLimit() {
+    $time = microtime(true);
+    expect(CronHelper::enforceExecutionLimit($time))->null();
+    try {
+      CronHelper::enforceExecutionLimit($time - CronHelper::DAEMON_EXECUTION_LIMIT);
+      self::fail('Execution limit exception not thrown.');
+    } catch(Exception $e) {
+      expect($e->getMessage())->equals('Maximum execution time has been reached.');
+    }
+  }
+
+  function _after() {
+    ORM::raw_execute('TRUNCATE ' . Setting::$_table);
+  }
+}
\ No newline at end of file