diff --git a/dev/tests/integration/testsuite/Magento/Customer/Controller/AccountTest.php b/dev/tests/integration/testsuite/Magento/Customer/Controller/AccountTest.php
index c169272b133bc..293a4c5a60363 100644
--- a/dev/tests/integration/testsuite/Magento/Customer/Controller/AccountTest.php
+++ b/dev/tests/integration/testsuite/Magento/Customer/Controller/AccountTest.php
@@ -685,7 +685,7 @@ public function testConfirmationEmailWithSpecialCharacters()
 
         $this->assertContains('To: ' . $email, $rawMessage);
 
-        $content = $message->getBody()->getPartContent(0);
+        $content = $message->getBody()->getParts()[0]->getRawContent();
         $confirmationUrl = $this->getConfirmationUrlFromMessageContent($content);
         $this->setRequestInfo($confirmationUrl, 'confirm');
         $this->clearCookieMessagesList();
diff --git a/dev/tests/integration/testsuite/Magento/Newsletter/Model/SubscriberTest.php b/dev/tests/integration/testsuite/Magento/Newsletter/Model/SubscriberTest.php
index 6c7aa204fded2..91f7c5202ad93 100644
--- a/dev/tests/integration/testsuite/Magento/Newsletter/Model/SubscriberTest.php
+++ b/dev/tests/integration/testsuite/Magento/Newsletter/Model/SubscriberTest.php
@@ -6,6 +6,9 @@
 
 namespace Magento\Newsletter\Model;
 
+/**
+ * \Magento\Newsletter\Model\Subscriber tests
+ */
 class SubscriberTest extends \PHPUnit\Framework\TestCase
 {
     /**
@@ -39,7 +42,7 @@ public function testEmailConfirmation()
         $this->assertContains(
             '/newsletter/subscriber/confirm/id/' . $this->_model->getSubscriberId()
             . '/code/ysayquyajua23iq29gxwu2eax2qb6gvy',
-            $transportBuilder->getSentMessage()->getRawMessage()
+            $transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent()
         );
         $this->assertEquals(Subscriber::STATUS_NOT_ACTIVE, $this->_model->getSubscriberStatus());
     }
diff --git a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Create/SaveTest.php b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Create/SaveTest.php
index 26b5f58760da8..874a08d39b56b 100644
--- a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Create/SaveTest.php
+++ b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Create/SaveTest.php
@@ -141,7 +141,7 @@ public function testSendEmailOnOrderSave()
         );
 
         $this->assertEquals($message->getSubject(), $subject);
-        $this->assertThat($message->getRawMessage(), $assert);
+        $this->assertThat($message->getBody()->getParts()[0]->getRawContent(), $assert);
     }
 
     /**
diff --git a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Creditmemo/AddCommentTest.php b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Creditmemo/AddCommentTest.php
index ac11f777daf9c..2e93784ee0e7c 100644
--- a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Creditmemo/AddCommentTest.php
+++ b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Creditmemo/AddCommentTest.php
@@ -54,7 +54,7 @@ public function testSendEmailOnAddCreditmemoComment()
         );
 
         $this->assertEquals($message->getSubject(), $subject);
-        $this->assertThat($message->getRawMessage(), $messageConstraint);
+        $this->assertThat($message->getBody()->getParts()[0]->getRawContent(), $messageConstraint);
     }
 
     /**
diff --git a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Creditmemo/SaveTest.php b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Creditmemo/SaveTest.php
index 4df7710bb4388..c347d1e0d69c1 100644
--- a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Creditmemo/SaveTest.php
+++ b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Creditmemo/SaveTest.php
@@ -51,7 +51,7 @@ public function testSendEmailOnCreditmemoSave()
         );
 
         $this->assertEquals($message->getSubject(), $subject);
-        $this->assertThat($message->getRawMessage(), $messageConstraint);
+        $this->assertThat($message->getBody()->getParts()[0]->getRawContent(), $messageConstraint);
     }
 
     /**
diff --git a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/EmailTest.php b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/EmailTest.php
index 337ad206ade91..83fe0ea446bef 100644
--- a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/EmailTest.php
+++ b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/EmailTest.php
@@ -82,7 +82,7 @@ public function testSendOrderEmail()
         );
 
         $this->assertEquals($message->getSubject(), $subject);
-        $this->assertThat($message->getRawMessage(), $assert);
+        $this->assertThat($message->getBody()->getParts()[0]->getRawContent(), $assert);
     }
 
     /**
diff --git a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/AddCommentTest.php b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/AddCommentTest.php
index 8643dfc66f1b9..9ee731d6efb0f 100644
--- a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/AddCommentTest.php
+++ b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/AddCommentTest.php
@@ -55,7 +55,7 @@ public function testSendEmailOnAddInvoiceComment()
         );
 
         $this->assertEquals($message->getSubject(), $subject);
-        $this->assertThat($message->getRawMessage(), $messageConstraint);
+        $this->assertThat($message->getBody()->getParts()[0]->getRawContent(), $messageConstraint);
     }
 
     /**
diff --git a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/EmailTest.php b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/EmailTest.php
index 39b7fc8ef0267..552c83824b5ba 100644
--- a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/EmailTest.php
+++ b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/EmailTest.php
@@ -59,7 +59,7 @@ public function testSendInvoiceEmail()
         );
 
         $this->assertEquals($message->getSubject(), $subject);
-        $this->assertThat($message->getRawMessage(), $messageConstraint);
+        $this->assertThat($message->getBody()->getParts()[0]->getRawContent(), $messageConstraint);
     }
 
     /**
diff --git a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/SaveTest.php b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/SaveTest.php
index d451bdcb287cf..901108588324c 100644
--- a/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/SaveTest.php
+++ b/dev/tests/integration/testsuite/Magento/Sales/Controller/Adminhtml/Order/Invoice/SaveTest.php
@@ -51,7 +51,7 @@ public function testSendEmailOnInvoiceSave()
         );
 
         $this->assertEquals($message->getSubject(), $subject);
-        $this->assertThat($message->getRawMessage(), $messageConstraint);
+        $this->assertThat($message->getBody()->getParts()[0]->getRawContent(), $messageConstraint);
     }
 
     /**
diff --git a/dev/tests/integration/testsuite/Magento/Sales/Model/Order/CreateTest.php b/dev/tests/integration/testsuite/Magento/Sales/Model/Order/CreateTest.php
index 4ff4ad384d3e4..656eee3dd7cbd 100644
--- a/dev/tests/integration/testsuite/Magento/Sales/Model/Order/CreateTest.php
+++ b/dev/tests/integration/testsuite/Magento/Sales/Model/Order/CreateTest.php
@@ -95,6 +95,6 @@ public function testSendEmailOnOrderPlace()
         );
 
         $this->assertEquals($message->getSubject(), $subject);
-        $this->assertThat($message->getRawMessage(), $assert);
+        $this->assertThat($message->getBody()->getParts()[0]->getRawContent(), $assert);
     }
 }
diff --git a/dev/tests/integration/testsuite/Magento/Shipping/Controller/Adminhtml/Order/Shipment/AddCommentTest.php b/dev/tests/integration/testsuite/Magento/Shipping/Controller/Adminhtml/Order/Shipment/AddCommentTest.php
index c86ad71e7d5ca..c3660afc1c4ca 100644
--- a/dev/tests/integration/testsuite/Magento/Shipping/Controller/Adminhtml/Order/Shipment/AddCommentTest.php
+++ b/dev/tests/integration/testsuite/Magento/Shipping/Controller/Adminhtml/Order/Shipment/AddCommentTest.php
@@ -54,7 +54,7 @@ public function testSendEmailOnShipmentCommentAdd()
         );
 
         $this->assertEquals($message->getSubject(), $subject);
-        $this->assertThat($message->getRawMessage(), $messageConstraint);
+        $this->assertThat($message->getBody()->getParts()[0]->getRawContent(), $messageConstraint);
     }
 
     /**
diff --git a/dev/tests/integration/testsuite/Magento/Shipping/Controller/Adminhtml/Order/Shipment/SaveTest.php b/dev/tests/integration/testsuite/Magento/Shipping/Controller/Adminhtml/Order/Shipment/SaveTest.php
index 4eb65678583aa..0a3c8a02655b2 100644
--- a/dev/tests/integration/testsuite/Magento/Shipping/Controller/Adminhtml/Order/Shipment/SaveTest.php
+++ b/dev/tests/integration/testsuite/Magento/Shipping/Controller/Adminhtml/Order/Shipment/SaveTest.php
@@ -51,7 +51,7 @@ public function testSendEmailOnShipmentSave()
         );
 
         $this->assertEquals($message->getSubject(), $subject);
-        $this->assertThat($message->getRawMessage(), $messageConstraint);
+        $this->assertThat($message->getBody()->getParts()[0]->getRawContent(), $messageConstraint);
     }
 
     /**
diff --git a/lib/internal/Magento/Framework/Mail/Message.php b/lib/internal/Magento/Framework/Mail/Message.php
index 1156a047ba370..0f9edd5dec00d 100644
--- a/lib/internal/Magento/Framework/Mail/Message.php
+++ b/lib/internal/Magento/Framework/Mail/Message.php
@@ -182,6 +182,8 @@ private function createMimeFromString($body, $messageType)
     {
         $part = new Part($body);
         $part->setCharset($this->zendMessage->getEncoding());
+        $part->setEncoding(Mime::ENCODING_QUOTEDPRINTABLE);
+        $part->setDisposition(Mime::DISPOSITION_INLINE);
         $part->setType($messageType);
         $mimeMessage = new \Zend\Mime\Message();
         $mimeMessage->addPart($part);
diff --git a/lib/internal/Magento/Framework/Mail/Test/Unit/MessageTest.php b/lib/internal/Magento/Framework/Mail/Test/Unit/MessageTest.php
index bea2a9ea91d38..c29ca4d261cc4 100644
--- a/lib/internal/Magento/Framework/Mail/Test/Unit/MessageTest.php
+++ b/lib/internal/Magento/Framework/Mail/Test/Unit/MessageTest.php
@@ -26,9 +26,10 @@ public function testSetBodyHtml()
 
         $part = $this->message->getBody()->getParts()[0];
         $this->assertEquals('text/html', $part->getType());
-        $this->assertEquals('8bit', $part->getEncoding());
+        $this->assertEquals('quoted-printable', $part->getEncoding());
         $this->assertEquals('utf-8', $part->getCharset());
         $this->assertEquals('body', $part->getContent());
+        $this->assertEquals('inline', $part->getDisposition());
     }
 
     public function testSetBodyText()
@@ -37,8 +38,9 @@ public function testSetBodyText()
 
         $part = $this->message->getBody()->getParts()[0];
         $this->assertEquals('text/plain', $part->getType());
-        $this->assertEquals('8bit', $part->getEncoding());
+        $this->assertEquals('quoted-printable', $part->getEncoding());
         $this->assertEquals('utf-8', $part->getCharset());
         $this->assertEquals('body', $part->getContent());
+        $this->assertEquals('inline', $part->getDisposition());
     }
 }