diff --git a/dev/tests/integration/testsuite/Magento/Newsletter/Model/SubscriberTest.php b/dev/tests/integration/testsuite/Magento/Newsletter/Model/SubscriberTest.php
index 370dc552458b9..dbf8bce795548 100644
--- a/dev/tests/integration/testsuite/Magento/Newsletter/Model/SubscriberTest.php
+++ b/dev/tests/integration/testsuite/Magento/Newsletter/Model/SubscriberTest.php
@@ -8,6 +8,7 @@
 namespace Magento\Newsletter\Model;
 
 use Magento\Customer\Api\CustomerRepositoryInterface;
+use Magento\Framework\Mail\EmailMessage;
 use Magento\Framework\Exception\LocalizedException;
 use Magento\Framework\Exception\NoSuchEntityException;
 use Magento\Framework\ObjectManagerInterface;
@@ -22,13 +23,16 @@
  */
 class SubscriberTest extends TestCase
 {
-    /** @var ObjectManagerInterface  */
+    private const CONFIRMATION_SUBSCRIBE = 'You have been successfully subscribed to our newsletter.';
+    private const CONFIRMATION_UNSUBSCRIBE = 'You have been unsubscribed from the newsletter.';
+
+    /** @var ObjectManagerInterface */
     private $objectManager;
 
     /** @var SubscriberFactory */
     private $subscriberFactory;
 
-    /** @var TransportBuilderMock  */
+    /** @var TransportBuilderMock */
     private $transportBuilder;
 
     /** @var CustomerRepositoryInterface */
@@ -89,27 +93,20 @@ public function testUnsubscribeSubscribe(): void
         $subscriber = $this->subscriberFactory->create();
         $this->assertSame($subscriber, $subscriber->loadByCustomerId(1));
         $this->assertEquals($subscriber, $subscriber->unsubscribe());
-        $this->assertStringContainsString(
-            'You have been unsubscribed from the newsletter.',
-            $this->getFilteredRawMessage($this->transportBuilder)
+        $this->assertConfirmationParagraphExists(
+            self::CONFIRMATION_UNSUBSCRIBE,
+            $this->transportBuilder->getSentMessage()
         );
+
         $this->assertEquals(Subscriber::STATUS_UNSUBSCRIBED, $subscriber->getSubscriberStatus());
         // Subscribe and verify
         $this->assertEquals(Subscriber::STATUS_SUBSCRIBED, $subscriber->subscribe('customer@example.com'));
         $this->assertEquals(Subscriber::STATUS_SUBSCRIBED, $subscriber->getSubscriberStatus());
-        $this->assertStringContainsString(
-            'You have been successfully subscribed to our newsletter.',
-            $this->getFilteredRawMessage($this->transportBuilder)
-        );
-    }
 
-    /**
-     * @param TransportBuilderMock $transportBuilderMock
-     * @return string
-     */
-    private function getFilteredRawMessage(TransportBuilderMock $transportBuilderMock): string
-    {
-        return $transportBuilderMock->getSentMessage()->getBody()->getParts()[0]->getRawContent();
+        $this->assertConfirmationParagraphExists(
+            self::CONFIRMATION_SUBSCRIBE,
+            $this->transportBuilder->getSentMessage()
+        );
     }
 
     /**
@@ -125,16 +122,17 @@ public function testUnsubscribeSubscribeByCustomerId(): void
         // Unsubscribe and verify
         $this->assertSame($subscriber, $subscriber->unsubscribeCustomerById(1));
         $this->assertEquals(Subscriber::STATUS_UNSUBSCRIBED, $subscriber->getSubscriberStatus());
-        $this->assertStringContainsString(
-            'You have been unsubscribed from the newsletter.',
-            $this->getFilteredRawMessage($this->transportBuilder)
+        $this->assertConfirmationParagraphExists(
+            self::CONFIRMATION_UNSUBSCRIBE,
+            $this->transportBuilder->getSentMessage()
         );
+
         // Subscribe and verify
         $this->assertSame($subscriber, $subscriber->subscribeCustomerById(1));
         $this->assertEquals(Subscriber::STATUS_SUBSCRIBED, $subscriber->getSubscriberStatus());
-        $this->assertStringContainsString(
-            'You have been successfully subscribed to our newsletter.',
-            $this->getFilteredRawMessage($this->transportBuilder)
+        $this->assertConfirmationParagraphExists(
+            self::CONFIRMATION_SUBSCRIBE,
+            $this->transportBuilder->getSentMessage()
         );
     }
 
@@ -152,9 +150,10 @@ public function testConfirm(): void
         $subscriber->subscribe($customerEmail);
         $subscriber->loadByEmail($customerEmail);
         $subscriber->confirm($subscriber->getSubscriberConfirmCode());
-        $this->assertStringContainsString(
-            'You have been successfully subscribed to our newsletter.',
-            $this->getFilteredRawMessage($this->transportBuilder)
+
+        $this->assertConfirmationParagraphExists(
+            self::CONFIRMATION_SUBSCRIBE,
+            $this->transportBuilder->getSentMessage()
         );
     }
 
@@ -189,4 +188,35 @@ public function testSubscribeUnconfirmedCustomerWithoutSubscription(): void
         $subscriber->subscribeCustomerById($customer->getId());
         $this->assertEquals(Subscriber::STATUS_UNCONFIRMED, $subscriber->getStatus());
     }
+
+    /**
+     * Verifies if Paragraph with specified message is in e-mail
+     *
+     * @param string $expectedMessage
+     * @param EmailMessage $message
+     */
+    private function assertConfirmationParagraphExists(string $expectedMessage, EmailMessage $message): void
+    {
+        $messageContent = $this->getMessageRawContent($message);
+
+        $emailDom = new \DOMDocument();
+        $emailDom->loadHTML($messageContent);
+
+        $emailXpath = new \DOMXPath($emailDom);
+        $greeting = $emailXpath->query("//p[contains(text(), '$expectedMessage')]");
+
+        $this->assertSame(1, $greeting->length, "Cannot find the confirmation paragraph in e-mail contents");
+    }
+
+    /**
+     * Returns raw content of provided message
+     *
+     * @param EmailMessage $message
+     * @return string
+     */
+    private function getMessageRawContent(EmailMessage $message): string
+    {
+        $emailParts = $message->getBody()->getParts();
+        return current($emailParts)->getRawContent();
+    }
 }