Fix newsletter subscriptions between stores

app/code/Magento/Newsletter/Model/ResourceModel/Subscriber.php

@@ -118,17 +118,37 @@ public function loadByEmail($subscriberEmail)
      */
     public function loadByCustomerData(\Magento\Customer\Api\Data\CustomerInterface $customer)
     {
-        $select = $this->connection->select()->from($this->getMainTable())->where('customer_id=:customer_id');
-
-        $result = $this->connection->fetchRow($select, ['customer_id' => $customer->getId()]);
+        $select = $this->connection
+            ->select()
+            ->from($this->getMainTable())
+            ->where('customer_id=:customer_id and store_id=:store_id');
+
+        $result = $this->connection
+            ->fetchRow(
+                $select,
+                [
+                    'customer_id' => $customer->getId(),
+                    'store_id' => $customer->getStoreId()
+                ]
+            );
 
         if ($result) {
             return $result;
         }
 
-        $select = $this->connection->select()->from($this->getMainTable())->where('subscriber_email=:subscriber_email');
-
-        $result = $this->connection->fetchRow($select, ['subscriber_email' => $customer->getEmail()]);
+        $select = $this->connection
+            ->select()
+            ->from($this->getMainTable())
+            ->where('subscriber_email=:subscriber_email and store_id=:store_id');
+
+        $result = $this->connection
+            ->fetchRow(
+                $select,
+                [
+                    'subscriber_email' => $customer->getEmail(),
+                    'store_id' => $customer->getStoreId()
+                ]
+            );
 
         if ($result) {
             return $result;

app/code/Magento/Newsletter/Model/Subscriber.php

@@ -349,6 +349,7 @@ public function loadByCustomerId($customerId)
     {
         try {
             $customerData = $this->customerRepository->getById($customerId);
+            $customerData->setStoreId($this->_storeManager->getStore()->getId());
             $data = $this->getResource()->loadByCustomerData($customerData);
             $this->addData($data);
             if (!empty($data) && $customerData->getId() && !$this->getCustomerId()) {

app/code/Magento/Newsletter/Test/Unit/Model/SubscriberTest.php

@@ -187,6 +187,12 @@ public function testUpdateSubscription()
         $customerDataMock->expects($this->once())->method('getStoreId')->willReturn('store_id');
         $customerDataMock->expects($this->once())->method('getEmail')->willReturn('email');
 
+        $storeModel = $this->getMockBuilder(\Magento\Store\Model\Store::class)
+            ->disableOriginalConstructor()
+            ->setMethods(['getId'])
+            ->getMock();
+        $this->storeManager->expects($this->any())->method('getStore')->willReturn($storeModel);
+
         $this->assertEquals($this->subscriber, $this->subscriber->updateSubscription($customerId));
     }
 

dev/tests/integration/testsuite/Magento/Customer/Controller/Adminhtml/IndexTest.php

@@ -347,6 +347,7 @@ public function testSaveActionExistingCustomerUnsubscribeNewsletter()
                 'email' => '[email protected]',
                 'firstname' => 'test firstname',
                 'lastname' => 'test lastname',
+                'sendemail_store_id' => 1
             ],
             'subscription' => '0'
         ];

dev/tests/integration/testsuite/Magento/Newsletter/_files/subscribers.php

@@ -28,7 +28,7 @@
 
 $subscriber = \Magento\TestFramework\Helper\Bootstrap::getObjectManager()
     ->create(\Magento\Newsletter\Model\Subscriber::class);
-$subscriber->setStoreId($otherStore)
+$subscriber->setStoreId($currentStore)
     // Intentionally setting ID to 0 instead of 2 to test fallback mechanism in Subscriber model
     ->setCustomerId(0)
     ->setSubscriberEmail('[email protected]')