MC-21868: Magento 2.3.3 notifications converted to attachments in MS Exchange - Disposition Header

Author: dyushkin

lib/internal/Magento/Framework/Mail/Message.php

@@ -171,7 +171,6 @@ 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);

lib/internal/Magento/Framework/Mail/MimePart.php

@@ -15,6 +15,9 @@
  */
 class MimePart implements MimePartInterface
 {
+    /**
+     * UTF-8 charset
+     */
     public const CHARSET_UTF8 = 'utf-8';
 
     /**
@@ -47,7 +50,7 @@ public function __construct(
         $content,
         ?string $type = MimeInterface::TYPE_HTML,
         ?string $fileName = null,
-        ?string $disposition = MimeInterface::DISPOSITION_INLINE,
+        ?string $disposition = null,
         ?string $encoding = MimeInterface::ENCODING_QUOTED_PRINTABLE,
         ?string $description = null,
         ?array $filters = [],

lib/internal/Magento/Framework/Mail/Test/Unit/MessageTest.php

@@ -29,7 +29,6 @@ public function testSetBodyHtml()
         $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()
@@ -41,6 +40,5 @@ public function testSetBodyText()
         $this->assertEquals('quoted-printable', $part->getEncoding());
         $this->assertEquals('utf-8', $part->getCharset());
         $this->assertEquals('body', $part->getContent());
-        $this->assertEquals('inline', $part->getDisposition());
     }
 }