diff --git a/lib/API/Endpoints/Services.php b/lib/API/Endpoints/Services.php
index 8a3bf55f5b..dbf7be6c78 100644
--- a/lib/API/Endpoints/Services.php
+++ b/lib/API/Endpoints/Services.php
@@ -9,18 +9,23 @@ use MailPoet\Services\Bridge;
 if(!defined('ABSPATH')) exit;
 
 class Services extends APIEndpoint {
+  public $bridge;
+
+  function __construct() {
+    $this->bridge = new Bridge();
+  }
+
   function verifyMailPoetKey($data = array()) {
     $key = isset($data['key']) ? trim($data['key']) : null;
 
     if(!$key) {
       return $this->badRequest(array(
-        APIError::BAD_REQUEST  => __('You need to specify a key.', 'mailpoet')
+        APIError::BAD_REQUEST  => __('Please specify a key.', 'mailpoet')
       ));
     }
 
     try {
-      $bridge = new Bridge($key);
-      $result = $bridge->checkKey();
+      $result = $this->bridge->checkKey($key);
     } catch(\Exception $e) {
       return $this->errorResponse(array(
         $e->getCode() => $e->getMessage()
diff --git a/lib/API/Endpoints/Settings.php b/lib/API/Endpoints/Settings.php
index 4bf02217cb..d3aeba82ec 100644
--- a/lib/API/Endpoints/Settings.php
+++ b/lib/API/Endpoints/Settings.php
@@ -3,6 +3,7 @@ namespace MailPoet\API\Endpoints;
 use MailPoet\API\Endpoint as APIEndpoint;
 use MailPoet\API\Error as APIError;
 use MailPoet\Models\Setting;
+use MailPoet\Services\Bridge;
 
 if(!defined('ABSPATH')) exit;
 
@@ -21,6 +22,12 @@ class Settings extends APIEndpoint {
       foreach($settings as $name => $value) {
         Setting::setValue($name, $value);
       }
+      if(!empty($settings['mta']['mailpoet_api_key'])
+          && Bridge::isMPSendingServiceEnabled()
+      ) {
+        $bridge = new Bridge();
+        $bridge->checkKey($settings['mta']['mailpoet_api_key']);
+      }
       return $this->successResponse(Setting::getAll());
     }
   }
diff --git a/lib/Config/Menu.php b/lib/Config/Menu.php
index fa345d7809..4b1b52ee8b 100644
--- a/lib/Config/Menu.php
+++ b/lib/Config/Menu.php
@@ -27,12 +27,7 @@ class Menu {
     $this->assets_url = $assets_url;
     $subscribers_feature = new SubscribersFeature();
     $this->subscribers_over_limit = $subscribers_feature->check();
-    if(self::isOnMailPoetAdminPage()) {
-      $show_notices = isset($_REQUEST['page'])
-        && stripos($_REQUEST['page'], 'mailpoet-newsletters') === false;
-      $checker = new ServicesChecker();
-      $this->mp_api_key_valid = $checker->checkMailPoetAPIKeyValid($show_notices);
-    }
+    $this->checkMailPoetAPIKey();
   }
 
   function init() {
@@ -516,6 +511,15 @@ class Menu {
     return (stripos($screen_id, 'mailpoet-') !== false);
   }
 
+  function checkMailPoetAPIKey(ServicesChecker $checker = null) {
+    if(self::isOnMailPoetAdminPage()) {
+      $show_notices = isset($_REQUEST['page'])
+        && stripos($_REQUEST['page'], 'mailpoet-newsletters') === false;
+      $checker = $checker ?: new ServicesChecker();
+      $this->mp_api_key_valid = $checker->checkMailPoetAPIKeyValid($show_notices);
+    }
+  }
+
   private function getLimitPerPage($model = null) {
     if($model === null) {
       return Listing\Handler::DEFAULT_LIMIT_PER_PAGE;
diff --git a/lib/Config/ServicesChecker.php b/lib/Config/ServicesChecker.php
index 9236790e4e..b24a9e817b 100644
--- a/lib/Config/ServicesChecker.php
+++ b/lib/Config/ServicesChecker.php
@@ -1,7 +1,6 @@
 <?php
 namespace MailPoet\Config;
 
-use MailPoet\Mailer\Mailer;
 use MailPoet\Models\Setting;
 use MailPoet\Models\Subscriber;
 use MailPoet\Services\Bridge;
@@ -16,7 +15,7 @@ class ServicesChecker {
       return null;
     }
 
-    $state = Setting::getValue('mta.mailpoet_api_key_state');
+    $state = Setting::getValue(Bridge::API_KEY_STATE_SETTING_NAME);
     if(empty($state['code']) || $state['code'] == Bridge::MAILPOET_KEY_VALID) {
       return true;
     }
@@ -30,7 +29,9 @@ class ServicesChecker {
         WPNotice::displayError($error);
       }
       return false;
-    } elseif($state['code'] == Bridge::MAILPOET_KEY_EXPIRING) {
+    } elseif($state['code'] == Bridge::MAILPOET_KEY_EXPIRING
+      && !empty($state['data']['expire_at'])
+    ) {
       $date = date('Y-m-d', strtotime($state['data']['expire_at']));
       $error = Helpers::replaceLinkTags(
         __('Your newsletters are awesome! Don\'t forget to [link]upgrade your MailPoet email plan[/link] by %s to keep sending them to your subscribers.', 'mailpoet'),
diff --git a/lib/Cron/Workers/SendingServiceKeyCheck.php b/lib/Cron/Workers/SendingServiceKeyCheck.php
index 1d145ac2bc..65ae044558 100644
--- a/lib/Cron/Workers/SendingServiceKeyCheck.php
+++ b/lib/Cron/Workers/SendingServiceKeyCheck.php
@@ -5,9 +5,7 @@ use Carbon\Carbon;
 use MailPoet\Cron\CronHelper;
 use MailPoet\Mailer\Mailer;
 use MailPoet\Models\SendingQueue;
-use MailPoet\Models\Subscriber;
 use MailPoet\Services\Bridge;
-use MailPoet\Util\Helpers;
 
 if(!defined('ABSPATH')) exit;
 
@@ -26,8 +24,7 @@ class SendingServiceKeyCheck {
 
   function initApi() {
     if(!$this->bridge) {
-      $mailer_config = Mailer::getMailerConfig();
-      $this->bridge = new Bridge($mailer_config['mailpoet_api_key']);
+      $this->bridge = new Bridge();
     }
   }
 
@@ -88,7 +85,12 @@ class SendingServiceKeyCheck {
     // abort if execution limit is reached
     CronHelper::enforceExecutionLimit($this->timer);
 
-    $result = $this->bridge->checkKey();
+    try {
+      $mailer_config = Mailer::getMailerConfig();
+      $result = $this->bridge->checkKey($mailer_config['mailpoet_api_key']);
+    } catch (\Exception $e) {
+      $result = array('code' => 503);
+    }
 
     if(empty($result['code']) || $result['code'] == 503) {
       // reschedule the check
diff --git a/lib/Mailer/Methods/MailPoet.php b/lib/Mailer/Methods/MailPoet.php
index 4e4939d1c0..218d3f6103 100644
--- a/lib/Mailer/Methods/MailPoet.php
+++ b/lib/Mailer/Methods/MailPoet.php
@@ -22,7 +22,7 @@ class MailPoet {
   }
 
   function send($newsletter, $subscriber, $extra_params = array()) {
-    if(!$this->services_checker->checkMailPoetAPIKeyValid()) {
+    if($this->services_checker->checkMailPoetAPIKeyValid() === false) {
       $response = __('MailPoet API key is invalid!', 'mailpoet');
       return Mailer::formatMailerSendErrorResult($response);
     }
diff --git a/lib/Services/Bridge.php b/lib/Services/Bridge.php
index a61a1194dd..9cb2d9845f 100644
--- a/lib/Services/Bridge.php
+++ b/lib/Services/Bridge.php
@@ -7,23 +7,37 @@ use MailPoet\Models\Setting;
 if(!defined('ABSPATH')) exit;
 
 class Bridge {
+  const API_KEY_STATE_SETTING_NAME = 'mta.mailpoet_api_key_state';
+
   const MAILPOET_KEY_VALID = 200;
   const MAILPOET_KEY_INVALID = 401;
   const MAILPOET_KEY_EXPIRING = 402;
 
   public $api;
 
-  function __construct($api_key) {
-    $this->api = new Bridge\API($api_key);
+  function __construct() {
   }
 
   static function isMPSendingServiceEnabled() {
-    $mailer_config = Mailer::getMailerConfig();
-    return !empty($mailer_config['method'])
-      && $mailer_config['method'] === Mailer::METHOD_MAILPOET;
+    try {
+      $mailer_config = Mailer::getMailerConfig();
+      return !empty($mailer_config['method'])
+        && $mailer_config['method'] === Mailer::METHOD_MAILPOET;
+    } catch (\Exception $e) {
+      return false;
+    }
   }
 
-  function checkKey() {
+  function initApi($api_key) {
+    if($this->api) {
+      $this->api->api_key = $api_key;
+    } else {
+      $this->api = new Bridge\API($api_key);
+    }
+  }
+
+  function checkKey($api_key) {
+    $this->initApi($api_key);
     $result = $this->api->checkKey();
     return $this->processResult($result);
   }
@@ -33,7 +47,7 @@ class Bridge {
       return false;
     }
     Setting::setValue(
-      'mta.mailpoet_api_key_state',
+      self::API_KEY_STATE_SETTING_NAME,
       array(
         'code' => (int)$result['code'],
         'data' => !empty($result['data']) ? $result['data'] : null,
@@ -43,6 +57,6 @@ class Bridge {
   }
 
   static function invalidateKey() {
-    Setting::setValue('mta.mailpoet_api_key_state', array('code' => 401));
+    Setting::setValue(self::API_KEY_STATE_SETTING_NAME, array('code' => 401));
   }
 }
diff --git a/tests/unit/API/Endpoints/ServicesTest.php b/tests/unit/API/Endpoints/ServicesTest.php
new file mode 100644
index 0000000000..a656780ff2
--- /dev/null
+++ b/tests/unit/API/Endpoints/ServicesTest.php
@@ -0,0 +1,65 @@
+<?php
+
+use Codeception\Util\Stub;
+use MailPoet\API\Endpoints\Services;
+use MailPoet\API\Response as APIResponse;
+use MailPoet\Services\Bridge;
+
+class ServicesTest extends MailPoetTest {
+  function _before() {
+    $this->services_endpoint = new Services();
+    $this->data = array('key' => '1234567890abcdef');
+  }
+
+  function testItRespondsWithErrorIfNoKeyIsGiven() {
+    $response = $this->services_endpoint->verifyMailPoetKey(array('key' => ''));
+    expect($response->status)->equals(APIResponse::STATUS_BAD_REQUEST);
+    expect($response->errors[0]['message'])->equals('Please specify a key.');
+  }
+
+  function testItRespondsWithSuccessIfKeyIsValid() {
+    $this->services_endpoint->bridge = Stub::make(
+      new Bridge(),
+      array('checkKey' => array('code' => Bridge::MAILPOET_KEY_VALID)),
+      $this
+    );
+    $response = $this->services_endpoint->verifyMailPoetKey($this->data);
+    expect($response->status)->equals(APIResponse::STATUS_OK);
+  }
+
+  function testItRespondsWithErrorIfKeyIsInvalid() {
+    $this->services_endpoint->bridge = Stub::make(
+      new Bridge(),
+      array('checkKey' => array('code' => Bridge::MAILPOET_KEY_INVALID)),
+      $this
+    );
+    $response = $this->services_endpoint->verifyMailPoetKey($this->data);
+    expect($response->status)->equals(APIResponse::STATUS_NOT_FOUND);
+  }
+
+  function testItRespondsWithErrorIfKeyIsExpiring() {
+    $date = new DateTime;
+    $this->services_endpoint->bridge = Stub::make(
+      new Bridge(),
+      array('checkKey' => array(
+        'code' => Bridge::MAILPOET_KEY_EXPIRING,
+        'data' => array('expire_at' => $date->format('c'))
+      )),
+      $this
+    );
+    $response = $this->services_endpoint->verifyMailPoetKey($this->data);
+    expect($response->status)->equals(APIResponse::STATUS_NOT_FOUND);
+    expect($response->errors[0]['message'])->contains($date->format('Y-m-d'));
+  }
+
+  function testItRespondsWithErrorIfServiceIsUnavailable() {
+    $this->services_endpoint->bridge = Stub::make(
+      new Bridge(),
+      array('checkKey' => array('code' => 503)),
+      $this
+    );
+    $response = $this->services_endpoint->verifyMailPoetKey($this->data);
+    expect($response->status)->equals(APIResponse::STATUS_NOT_FOUND);
+    expect($response->errors[0]['message'])->contains('503');
+  }
+}
\ No newline at end of file
diff --git a/tests/unit/Config/MenuTest.php b/tests/unit/Config/MenuTest.php
new file mode 100644
index 0000000000..a087d7324f
--- /dev/null
+++ b/tests/unit/Config/MenuTest.php
@@ -0,0 +1,59 @@
+<?php
+use Codeception\Util\Stub;
+use MailPoet\Config\Menu;
+use MailPoet\Config\Renderer;
+use MailPoet\Config\ServicesChecker;
+
+class MenuTest extends MailPoetTest {
+  function testItReturnsTrueIfCurrentPageBelongsToMailpoet() {
+    $result = Menu::isOnMailPoetAdminPage(null, 'somepage');
+    expect($result)->false();
+    $result = Menu::isOnMailPoetAdminPage(null, 'mailpoet-newsletters');
+    expect($result)->true();
+  }
+
+  function testItRespectsExclusionsWhenCheckingMPPages() {
+    $exclude = array('mailpoet-welcome');
+    $result = Menu::isOnMailPoetAdminPage($exclude, 'mailpoet-welcome');
+    expect($result)->false();
+    $result = Menu::isOnMailPoetAdminPage($exclude, 'mailpoet-newsletters');
+    expect($result)->true();
+  }
+
+  function testItWorksWithRequestDataWhenCheckingMPPages() {
+    $_REQUEST['page'] = 'mailpoet-newsletters';
+    $result = Menu::isOnMailPoetAdminPage();
+    expect($result)->true();
+
+    $_REQUEST['page'] = 'blah';
+    $result = Menu::isOnMailPoetAdminPage();
+    expect($result)->false();
+
+    unset($_REQUEST['page']);
+    $result = Menu::isOnMailPoetAdminPage();
+    expect($result)->false();
+  }
+
+  function testItChecksMailpoetAPIKey() {
+    $renderer = Stub::make(new Renderer());
+    $assets_url = '';
+    $menu = new Menu($renderer, $assets_url);
+
+    $_REQUEST['page'] = 'mailpoet-newsletters';
+    $checker = Stub::make(
+      new ServicesChecker(),
+      array('checkMailPoetAPIKeyValid' => true),
+      $this
+    );
+    $menu->checkMailPoetAPIKey($checker);
+    expect($menu->mp_api_key_valid)->true();
+
+    $checker = Stub::make(
+      new ServicesChecker(),
+      array('checkMailPoetAPIKeyValid' => false),
+      $this
+    );
+    $menu->checkMailPoetAPIKey($checker);
+    expect($menu->mp_api_key_valid)->false();
+  }
+}
\ No newline at end of file
diff --git a/tests/unit/Config/ServicesCheckerTest.php b/tests/unit/Config/ServicesCheckerTest.php
new file mode 100644
index 0000000000..e37e07b156
--- /dev/null
+++ b/tests/unit/Config/ServicesCheckerTest.php
@@ -0,0 +1,70 @@
+<?php
+
+use MailPoet\Config\ServicesChecker;
+use MailPoet\Mailer\Mailer;
+use MailPoet\Models\Setting;
+use MailPoet\Services\Bridge;
+
+class ServicesCheckerTest extends MailPoetTest {
+  function testItDoesNotCheckKeyIfMPSendingServiceIsDisabled() {
+    $this->disableMailPoetSendingMethod();
+    $result = ServicesChecker::checkMailPoetAPIKeyValid();
+    expect($result)->null();
+  }
+
+  function testItChecksKeyValidity() {
+    $this->setMailPoetSendingMethod();
+    Setting::setValue(
+      Bridge::API_KEY_STATE_SETTING_NAME,
+      array('code' => Bridge::MAILPOET_KEY_VALID)
+    );
+    $result = ServicesChecker::checkMailPoetAPIKeyValid();
+    expect($result)->true();
+
+    Setting::setValue(
+      Bridge::API_KEY_STATE_SETTING_NAME,
+      array('code' => Bridge::MAILPOET_KEY_INVALID)
+    );
+    $result = ServicesChecker::checkMailPoetAPIKeyValid();
+    expect($result)->false();
+
+    Setting::setValue(
+      Bridge::API_KEY_STATE_SETTING_NAME,
+      array(
+        'code' => Bridge::MAILPOET_KEY_EXPIRING,
+        'data' => array('expire_at' => date('c'))
+      )
+    );
+    $result = ServicesChecker::checkMailPoetAPIKeyValid();
+    expect($result)->true();
+
+    Setting::setValue(
+      Bridge::API_KEY_STATE_SETTING_NAME,
+      array(
+        'code' => 503
+      )
+    );
+    $result = ServicesChecker::checkMailPoetAPIKeyValid();
+    expect($result)->true();
+  }
+
+
+  private function setMailPoetSendingMethod() {
+    Setting::setValue(
+      Mailer::MAILER_CONFIG_SETTING_NAME,
+      array(
+        'method' => 'MailPoet',
+        'mailpoet_api_key' => 'some_key',
+      )
+    );
+  }
+
+  private function disableMailPoetSendingMethod() {
+    Setting::setValue(
+      Mailer::MAILER_CONFIG_SETTING_NAME,
+      array(
+        'method' => 'PHPMail',
+      )
+    );
+  }
+}
\ No newline at end of file
diff --git a/tests/unit/Cron/Workers/BounceTest.php b/tests/unit/Cron/Workers/BounceTest.php
index 985a61039e..66053cd25e 100644
--- a/tests/unit/Cron/Workers/BounceTest.php
+++ b/tests/unit/Cron/Workers/BounceTest.php
@@ -29,8 +29,6 @@ class BounceTest extends MailPoetTest {
 
     $this->bounce = new Bounce(microtime(true));
 
-    $api =
-
     $this->bounce->api = new MailPoet\Cron\Workers\Bounce\MockAPI('key');
   }
 
@@ -42,12 +40,6 @@ class BounceTest extends MailPoetTest {
     expect(Bounce::BATCH_SIZE)->equals(100);
   }
 
-  function testItChecksIfCurrentSendingMethodIsMailpoet() {
-    expect(Bounce::checkBounceSyncAvailable())->false();
-    $this->setMailPoetSendingMethod();
-    expect(Bounce::checkBounceSyncAvailable())->true();
-  }
-
   function testItThrowsExceptionWhenExecutionLimitIsReached() {
     try {
       $bounce = new Bounce(microtime(true) - CronHelper::DAEMON_EXECUTION_LIMIT);
diff --git a/tests/unit/Cron/Workers/SendingServiceKeyCheckTest.php b/tests/unit/Cron/Workers/SendingServiceKeyCheckTest.php
new file mode 100644
index 0000000000..67f37b7c2a
--- /dev/null
+++ b/tests/unit/Cron/Workers/SendingServiceKeyCheckTest.php
@@ -0,0 +1,202 @@
+<?php
+
+use Carbon\Carbon;
+use Codeception\Util\Stub;
+use MailPoet\API\Endpoints\Cron;
+use MailPoet\Cron\CronHelper;
+use MailPoet\Cron\Workers\SendingServiceKeyCheck as SSKeyCheck;
+use MailPoet\Cron\Workers\SendingServiceKeyCheck\API;
+use MailPoet\Mailer\Mailer;
+use MailPoet\Models\SendingQueue;
+use MailPoet\Models\Setting;
+use MailPoet\Services\Bridge;
+use MailPoet\Util\Helpers;
+
+class SendingServiceKeyCheckTest extends MailPoetTest {
+  function _before() {
+    $this->emails = array(
+      'soft_bounce@example.com',
+      'hard_bounce@example.com',
+      'good_address@example.com'
+    );
+
+    $this->sskeycheck = new SSKeyCheck(microtime(true));
+  }
+
+  function testItConstructs() {
+    expect($this->sskeycheck->timer)->notEmpty();
+  }
+
+  function testItThrowsExceptionWhenExecutionLimitIsReached() {
+    try {
+      $sskeycheck = new SSKeyCheck(microtime(true) - CronHelper::DAEMON_EXECUTION_LIMIT);
+      self::fail('Maximum execution time limit exception was not thrown.');
+    } catch(\Exception $e) {
+      expect($e->getMessage())->equals('Maximum execution time has been reached.');
+    }
+  }
+
+  function testItSchedulesSendingServiceKeyCheck() {
+    expect(SendingQueue::where('type', SSKeyCheck::TASK_TYPE)->findMany())->isEmpty();
+    SSKeyCheck::schedule();
+    expect(SendingQueue::where('type', SSKeyCheck::TASK_TYPE)->findMany())->notEmpty();
+  }
+
+  function testItDoesNotScheduleSendingServiceKeyCheckTwice() {
+    expect(count(SendingQueue::where('type', SSKeyCheck::TASK_TYPE)->findMany()))->equals(0);
+    SSKeyCheck::schedule();
+    expect(count(SendingQueue::where('type', SSKeyCheck::TASK_TYPE)->findMany()))->equals(1);
+    SSKeyCheck::schedule();
+    expect(count(SendingQueue::where('type', SSKeyCheck::TASK_TYPE)->findMany()))->equals(1);
+  }
+
+  function testItCanGetScheduledQueues() {
+    expect(SSKeyCheck::getScheduledQueues())->isEmpty();
+    $this->createScheduledQueue();
+    expect(SSKeyCheck::getScheduledQueues())->notEmpty();
+  }
+
+  function testItCanGetRunningQueues() {
+    expect(SSKeyCheck::getRunningQueues())->isEmpty();
+    $this->createRunningQueue();
+    expect(SSKeyCheck::getRunningQueues())->notEmpty();
+  }
+
+  function testItCanGetAllDueQueues() {
+    expect(SSKeyCheck::getAllDueQueues())->isEmpty();
+
+    // scheduled for now
+    $this->createScheduledQueue();
+
+    // running
+    $this->createRunningQueue();
+
+    // scheduled in the future (should not be retrieved)
+    $queue = $this->createScheduledQueue();
+    $queue->scheduled_at = Carbon::createFromTimestamp(current_time('timestamp'))->addDays(7);
+    $queue->save();
+
+    // completed (should not be retrieved)
+    $queue = $this->createRunningQueue();
+    $queue->status = SendingQueue::STATUS_COMPLETED;
+    $queue->save();
+
+    expect(count(SSKeyCheck::getAllDueQueues()))->equals(2);
+  }
+
+  function testItCanGetFutureQueues() {
+    expect(SSKeyCheck::getFutureQueues())->isEmpty();
+    $queue = $this->createScheduledQueue();
+    $queue->scheduled_at = Carbon::createFromTimestamp(current_time('timestamp'))->addDays(7);
+    $queue->save();
+    expect(count(SSKeyCheck::getFutureQueues()))->notEmpty();
+  }
+
+  function testItFailsToProcessWithoutMailPoetMethodSetUp() {
+    expect($this->sskeycheck->process())->false();
+  }
+
+  function testItFailsToProcessWithoutQueues() {
+    $this->setMailPoetSendingMethod();
+    expect($this->sskeycheck->process())->false();
+  }
+
+  function testItProcesses() {
+    $this->setMailPoetSendingMethod();
+    $this->createScheduledQueue();
+    $this->createRunningQueue();
+    expect($this->sskeycheck->process())->true();
+  }
+
+  function testItPreparesSendingServiceKeyCheckQueue() {
+    $queue = $this->createScheduledQueue();
+    $this->sskeycheck->prepareQueue($queue);
+    expect($queue->status)->null();
+  }
+
+  function testItProcessesSSKeyCheckQueue() {
+    $this->sskeycheck->bridge = Stub::make(
+      new Bridge,
+      array('checkKey' => array('code' => Bridge::MAILPOET_KEY_VALID)),
+      $this
+    );
+    $this->setMailPoetSendingMethod();
+    $queue = $this->createRunningQueue();
+    $this->sskeycheck->prepareQueue($queue);
+    $this->sskeycheck->processQueue($queue);
+    expect($queue->status)->equals(SendingQueue::STATUS_COMPLETED);
+  }
+
+  function testItReschedulesCheckOnException() {
+    $this->sskeycheck->bridge = Stub::make(
+      new Bridge,
+      array('checkKey' => function () { throw new \Exception(); }),
+      $this
+    );
+    $this->setMailPoetSendingMethod();
+    $queue = $this->createRunningQueue();
+    $scheduled_at = $queue->scheduled_at;
+    $this->sskeycheck->prepareQueue($queue);
+    $this->sskeycheck->processQueue($queue);
+    expect($scheduled_at < $queue->scheduled_at)->true();
+  }
+
+  function testItReschedulesCheckOnError() {
+    $this->sskeycheck->bridge = Stub::make(
+      new Bridge,
+      array('checkKey' => array('code' => 503)),
+      $this
+    );
+    $this->setMailPoetSendingMethod();
+    $queue = $this->createRunningQueue();
+    $scheduled_at = $queue->scheduled_at;
+    $this->sskeycheck->prepareQueue($queue);
+    $this->sskeycheck->processQueue($queue);
+    expect($scheduled_at < $queue->scheduled_at)->true();
+  }
+
+  function testItCalculatesNextRunDateWithinNextWeekBoundaries() {
+    $current_date = Carbon::createFromTimestamp(current_time('timestamp'));
+    $next_run_date = SSKeyCheck::getNextRunDate();
+    $difference = $next_run_date->diffInDays($current_date);
+    // Subtract days left in the current week
+    $difference -= (Carbon::DAYS_PER_WEEK - $current_date->format('N'));
+    expect($difference)->lessOrEquals(7);
+    expect($difference)->greaterOrEquals(0);
+  }
+
+  private function setMailPoetSendingMethod() {
+    Setting::setValue(
+      Mailer::MAILER_CONFIG_SETTING_NAME,
+      array(
+        'method' => 'MailPoet',
+        'mailpoet_api_key' => 'some_key',
+      )
+    );
+  }
+
+  private function createScheduledQueue() {
+    $queue = SendingQueue::create();
+    $queue->type = SSKeyCheck::TASK_TYPE;
+    $queue->status = SendingQueue::STATUS_SCHEDULED;
+    $queue->scheduled_at = Carbon::createFromTimestamp(current_time('timestamp'));
+    $queue->newsletter_id = 0;
+    $queue->save();
+    return $queue;
+  }
+
+  private function createRunningQueue() {
+    $queue = SendingQueue::create();
+    $queue->type = SSKeyCheck::TASK_TYPE;
+    $queue->status = null;
+    $queue->scheduled_at = Carbon::createFromTimestamp(current_time('timestamp'));
+    $queue->newsletter_id = 0;
+    $queue->save();
+    return $queue;
+  }
+
+  function _after() {
+    ORM::raw_execute('TRUNCATE ' . Setting::$_table);
+    ORM::raw_execute('TRUNCATE ' . SendingQueue::$_table);
+  }
+}
\ No newline at end of file
diff --git a/tests/unit/Mailer/Methods/MailPoetAPITest.php b/tests/unit/Mailer/Methods/MailPoetAPITest.php
index d0b1f8854d..0119c521ce 100644
--- a/tests/unit/Mailer/Methods/MailPoetAPITest.php
+++ b/tests/unit/Mailer/Methods/MailPoetAPITest.php
@@ -1,6 +1,8 @@
 <?php
 
+use Codeception\Util\Stub;
 use MailPoet\Mailer\Methods\MailPoet;
+use MailPoet\Config\ServicesChecker;
 
 class MailPoetAPITest extends MailPoetTest {
   function _before() {
@@ -103,6 +105,21 @@ class MailPoetAPITest extends MailPoetTest {
       ->equals('Basic ' . base64_encode('api:' . $this->settings['api_key']));
   }
 
+  function testItWillNotSendIfApiKeyIsMarkedInvalid() {
+    if(getenv('WP_TEST_MAILER_ENABLE_SENDING') !== 'true') return;
+    $this->mailer->api_key = 'someapi';
+    $this->mailer->services_checker = Stub::make(
+      new ServicesChecker(),
+      array('checkMailPoetAPIKeyValid' => false),
+      $this
+    );
+    $result = $this->mailer->send(
+      $this->newsletter,
+      $this->subscriber
+    );
+    expect($result['response'])->false();
+  }
+
   function testItCannotSendWithoutProperApiKey() {
     if(getenv('WP_TEST_MAILER_ENABLE_SENDING') !== 'true') return;
     $this->mailer->api_key = 'someapi';
diff --git a/tests/unit/Services/BridgeTest.php b/tests/unit/Services/BridgeTest.php
new file mode 100644
index 0000000000..8604ed650f
--- /dev/null
+++ b/tests/unit/Services/BridgeTest.php
@@ -0,0 +1,82 @@
+<?php
+
+use Codeception\Util\Stub;
+use MailPoet\Services\Bridge;
+use MailPoet\Services\Bridge\API;
+use MailPoet\Mailer\Mailer;
+use MailPoet\Models\Setting;
+
+require_once('BridgeTestMockAPI.php');
+
+class BridgeTest extends MailPoetTest {
+  function _before() {
+    $this->valid_key = 'abcdefghijklmnopqrstuvwxyz';
+    $this->invalid_key = '401' . $this->valid_key;
+    $this->expiring_key = '402' . $this->valid_key;
+    $this->uncheckable_key = '503' . $this->valid_key;
+
+    $this->bridge = new Bridge();
+
+    $this->bridge->api = new MailPoet\Services\Bridge\MockAPI('key');
+  }
+
+  function testItChecksIfCurrentSendingMethodIsMailpoet() {
+    expect(Bridge::isMPSendingServiceEnabled())->false();
+    $this->setMailPoetSendingMethod();
+    expect(Bridge::isMPSendingServiceEnabled())->true();
+  }
+
+  function testMPCheckReturnsFalseWhenMailerThrowsException() {
+    Setting::setValue(Mailer::MAILER_CONFIG_SETTING_NAME, '');
+    expect(Bridge::isMPSendingServiceEnabled())->false();
+  }
+
+  function testItInstantiatesDefaultAPI() {
+    $this->bridge->api = null;
+    $this->bridge->initApi(null);
+    expect($this->bridge->api instanceof API)->true();
+  }
+
+  function testItChecksValidKey() {
+    $result = $this->bridge->checkKey($this->valid_key);
+    expect($result)->notEmpty();
+    expect($result['code'])->equals(Bridge::MAILPOET_KEY_VALID);
+
+    $result = $this->bridge->checkKey($this->invalid_key);
+    expect($result)->notEmpty();
+    expect($result['code'])->equals(Bridge::MAILPOET_KEY_INVALID);
+
+    $result = $this->bridge->checkKey($this->expiring_key);
+    expect($result)->notEmpty();
+    expect($result['code'])->equals(Bridge::MAILPOET_KEY_EXPIRING);
+    expect($result['data']['expire_at'])->notEmpty();
+  }
+
+  function testItReturnsFalseOnEmptyAPIResponseCode() {
+    $api = Stub::make(new API(null), array('checkKey' => array()), $this);
+    $this->bridge->api = $api;
+    $result = $this->bridge->checkKey($this->valid_key);
+    expect($result)->false();
+  }
+
+  function testItInvalidatesKey() {
+    Setting::setValue(Bridge::API_KEY_STATE_SETTING_NAME, array('code' => 200));
+    Bridge::invalidateKey();
+    $value = Setting::getValue(Bridge::API_KEY_STATE_SETTING_NAME);
+    expect($value)->equals(array('code' => 401));
+  }
+
+  private function setMailPoetSendingMethod() {
+    Setting::setValue(
+      Mailer::MAILER_CONFIG_SETTING_NAME,
+      array(
+        'method' => 'MailPoet',
+        'mailpoet_api_key' => 'some_key',
+      )
+    );
+  }
+
+  function _after() {
+    ORM::raw_execute('TRUNCATE ' . Setting::$_table);
+  }
+}
\ No newline at end of file
diff --git a/tests/unit/Services/BridgeTestMockAPI.php b/tests/unit/Services/BridgeTestMockAPI.php
new file mode 100644
index 0000000000..f130218a45
--- /dev/null
+++ b/tests/unit/Services/BridgeTestMockAPI.php
@@ -0,0 +1,42 @@
+<?php
+namespace MailPoet\Services\Bridge;
+
+use Carbon\Carbon;
+
+if(!defined('ABSPATH')) exit;
+
+class MockAPI {
+  public $api_key;
+
+  function __construct($api_key) {
+    $this->api_key = $api_key;
+  }
+
+  function checkKey() {
+    // if key begins with these codes, return them
+    $regex = '/^(401|402|503)/';
+    $code = preg_match($regex, $this->api_key, $m) ? $m[1] : 200;
+    return $this->processResponse($code);
+  }
+
+  private function processResponse($code) {
+    switch($code) {
+      case 200:
+        $body = array('subscriber_limit' => 10000);
+        break;
+      case 402:
+        $body = array(
+          'subscriber_limit' => 10000,
+          'expire_at' => Carbon::createFromTimestamp(current_time('timestamp'))
+            ->addMonth()->format('c')
+        );
+        break;
+      case 401:
+      default:
+        $body = null;
+        break;
+    }
+
+    return array('code' => $code, 'data' => $body);
+  }
+}