diff --git a/composer.json b/composer.json
index a7c4c8d..db41c6a 100644
--- a/composer.json
+++ b/composer.json
@@ -19,7 +19,8 @@
         "illuminate/contracts": "^5.3 | ^6.0 | ^7.0",
         "illuminate/support": "^5.3 | ^6.0 | ^7.0",
         "illuminate/mail": "^5.3 | ^6.0 | ^7.0 | ^8.0",
-        "squizlabs/php_codesniffer": "^3.5"
+        "squizlabs/php_codesniffer": "^3.5",
+        "masterminds/html5": "^2.0"
     },
     "require-dev": {
         "php": ">=7.0",
diff --git a/src/Listeners/SwiftEmbedImages.php b/src/Listeners/SwiftEmbedImages.php
index f286513..4f37a50 100644
--- a/src/Listeners/SwiftEmbedImages.php
+++ b/src/Listeners/SwiftEmbedImages.php
@@ -8,6 +8,7 @@
 use Eduardokum\LaravelMailAutoEmbed\Embedder\Base64Embedder;
 use Eduardokum\LaravelMailAutoEmbed\Embedder\Embedder;
 use Eduardokum\LaravelMailAutoEmbed\Models\EmbeddableEntity;
+use Masterminds\HTML5;
 use ReflectionClass;
 use Swift_Events_SendEvent;
 use Swift_Events_SendListener;
@@ -61,8 +62,9 @@ private function attachImages()
         $body = $this->message->getBody();
 
         // Parse document
-        $document = new DOMDocument();
-        if (!$document->loadHTML($body)) {
+        $parser = new HTML5();
+        $document = $parser->loadHTML($body);
+        if (!$document) {
             // Cannot read
             return;
         }
@@ -71,7 +73,7 @@ private function attachImages()
         $this->attachImagesToDom($document);
 
         // Replace body
-        $this->message->setBody($document->saveHTML());
+        $this->message->setBody($parser->saveHTML($document));
     }
 
     /**
diff --git a/tests/FormatTest.php b/tests/FormatTest.php
new file mode 100644
index 0000000..3e4d365
--- /dev/null
+++ b/tests/FormatTest.php
@@ -0,0 +1,45 @@
+<?php
+
+namespace Eduardokum\LaravelMailAutoEmbed\Tests;
+
+use Eduardokum\LaravelMailAutoEmbed\Listeners\SwiftEmbedImages;
+use Eduardokum\LaravelMailAutoEmbed\Tests\Traits\InteractsWithSwift;
+
+/**
+ * Tests some scenarios, like HTML5 mails and mail with "invalid" HTML that mail clients
+ * like
+ */
+class FormatTest extends TestCase
+{
+    use InteractsWithSwift;
+    private const HANDLE_CONFIG = [
+        'enabled' => true,
+        'method' => 'attachment'
+    ];
+
+    /**
+     * @test
+     */
+    public function testValidHtml5Message()
+    {
+        $message = $this->handleBeforeSendPerformedEvent('formats/html5-valid.html', self::HANDLE_CONFIG);
+
+        $this->assertEmailImageTags([
+            'url' => 'cid:',
+            'entity' => 'cid:',
+        ], $message->getBody());
+    }
+
+    /**
+     * @test
+     */
+    public function testUserGeneratedHtml5Message()
+    {
+        $message = $this->handleBeforeSendPerformedEvent('formats/html5-user-generated.html', self::HANDLE_CONFIG);
+
+        $this->assertEmailImageTags([
+            'url' => 'cid:',
+            'entity' => 'cid:',
+        ], $message->getBody());
+    }
+}
diff --git a/tests/MailTest.php b/tests/MailTest.php
index 2c6c39d..1a39529 100644
--- a/tests/MailTest.php
+++ b/tests/MailTest.php
@@ -3,48 +3,11 @@
 namespace Eduardokum\LaravelMailAutoEmbed\Tests;
 
 use Eduardokum\LaravelMailAutoEmbed\Listeners\SwiftEmbedImages;
+use Eduardokum\LaravelMailAutoEmbed\Tests\Traits\InteractsWithSwift;
 
 class MailTest extends TestCase
 {
-    /**
-     * @param  string  $htmlMessage
-     * @return \Swift_Message
-     */
-    private function createSwiftMessage($htmlMessage)
-    {
-        $message = new \Swift_Message('test', $htmlMessage);
-
-        return $message;
-    }
-
-    /**
-     * @param  \Swift_Message  $message
-     * @return \Swift_Events_SendEvent
-     */
-    private function createSwiftEvent(\Swift_Message $message)
-    {
-        $dispatcher = new \Swift_Events_SimpleEventDispatcher();
-        $transport = new \Swift_Transport_NullTransport($dispatcher);
-        $event = new \Swift_Events_SendEvent($transport, $message);
-
-        return $event;
-    }
-
-    /**
-     * @param  string  $libraryFile
-     * @param  array   $options
-     * @return \Swift_Message
-     */
-    private function handleBeforeSendPerformedEvent($libraryFile, $options)
-    {
-        $htmlMessage = $this->getLibraryFile($libraryFile);
-        $message = $this->createSwiftMessage($htmlMessage);
-
-        $embedPlugin = new SwiftEmbedImages($options);
-        $embedPlugin->beforeSendPerformed($this->createSwiftEvent($message));
-
-        return $message;
-    }
+    use InteractsWithSwift;
 
     /**
      * @test
@@ -181,28 +144,4 @@ public function testDoesntHandleSendPerformedEvent()
             $embedPlugin->sendPerformed($this->createSwiftEvent($message))
         );
     }
-
-    /**
-     * Check the body for image tags with the given keys as comment preceding them.
-     * @param array $expectations
-     * @param string $body
-     * @return void
-     */
-    protected function assertEmailImageTags($expectations, $body)
-    {
-        foreach ($expectations as $comment => $src) {
-            // Gimmick of using a DOMDocument parser
-            $src = str_replace('\\', '%5C', \htmlspecialchars($src));
-
-            // Fix for PHPUnit <8.0
-            // phpcs:ignore Generic.Files.LineLength.TooLong
-            $method = \method_exists($this, 'assertStringContainsString') ? 'assertStringContainsString' : 'assertContains';
-
-            // Check if the string is contained within the string
-            $this->$method(
-                sprintf('<!-- %s --><img src="%s', $comment, $src),
-                $body
-            );
-        }
-    }
 }
diff --git a/tests/Traits/InteractsWithSwift.php b/tests/Traits/InteractsWithSwift.php
new file mode 100644
index 0000000..99f8dad
--- /dev/null
+++ b/tests/Traits/InteractsWithSwift.php
@@ -0,0 +1,72 @@
+<?php
+
+namespace Eduardokum\LaravelMailAutoEmbed\Tests\Traits;
+
+use Eduardokum\LaravelMailAutoEmbed\Listeners\SwiftEmbedImages;
+
+/**
+ * Shared code for creating messages and events
+ */
+trait InteractsWithSwift
+{
+    /**
+     * @param  string  $htmlMessage
+     * @return \Swift_Message
+     */
+    protected function createSwiftMessage($htmlMessage)
+    {
+        $message = new \Swift_Message('test', $htmlMessage);
+
+        return $message;
+    }
+
+    /**
+     * @param  \Swift_Message  $message
+     * @return \Swift_Events_SendEvent
+     */
+    protected function createSwiftEvent(\Swift_Message $message)
+    {
+        $dispatcher = new \Swift_Events_SimpleEventDispatcher();
+        $transport = new \Swift_Transport_NullTransport($dispatcher);
+        $event = new \Swift_Events_SendEvent($transport, $message);
+
+        return $event;
+    }
+
+    /**
+     * @param  string  $libraryFile
+     * @param  array   $options
+     * @return \Swift_Message
+     */
+    protected function handleBeforeSendPerformedEvent($libraryFile, $options)
+    {
+        $htmlMessage = $this->getLibraryFile($libraryFile);
+        $message = $this->createSwiftMessage($htmlMessage);
+
+        $embedPlugin = new SwiftEmbedImages($options);
+        $embedPlugin->beforeSendPerformed($this->createSwiftEvent($message));
+
+        return $message;
+    }
+
+    /**
+     * Check the body for image tags with the given keys as comment preceding them.
+     * @param array $expectations
+     * @param string $body
+     * @return void
+     */
+    protected function assertEmailImageTags($expectations, $body)
+    {
+        foreach ($expectations as $comment => $src) {
+            // Fix for PHPUnit <8.0
+            // phpcs:ignore Generic.Files.LineLength.TooLong
+            $method = \method_exists($this, 'assertStringContainsString') ? 'assertStringContainsString' : 'assertContains';
+
+            // Check if the string is contained within the string
+            $this->$method(
+                sprintf('<!-- %s --><img src="%s', $comment, $src),
+                $body
+            );
+        }
+    }
+}
diff --git a/tests/lib/formats/html5-user-generated.html b/tests/lib/formats/html5-user-generated.html
new file mode 100644
index 0000000..9a082c8
--- /dev/null
+++ b/tests/lib/formats/html5-user-generated.html
@@ -0,0 +1,72 @@
+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+    <meta charset="utf-8">
+</head>
+
+<body>
+    <main>
+        <article>
+            <h1>Lorem Ipsum</h1>
+
+            <p>
+                Lorem ipsum dolor sit amet consectetur adipisicing elit. Nulla, dolorum assumenda aliquam blanditiis,
+                necessitatibus mollitia delectus sapiente amet earum minima qui non deserunt quidem, doloremque
+                architecto voluptatem eveniet illo aperiam.
+            </p>
+
+            <p>
+                <!-- Source: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/colgroup -->
+                <table>
+                    <caption>Superheros and sidekicks</caption>
+                    <colgroup>
+                        <col>
+                        <col span="2" class="batman">
+                        <col span="2" class="flash">
+                    </colgroup>
+                    <tr>
+                        <td> </td>
+                        <th scope="col">Batman</th>
+                        <th scope="col">Robin</th>
+                        <th scope="col">The Flash</th>
+                        <th scope="col">Kid Flash</th>
+                    </tr>
+                    <tr>
+                        <th scope="row">Skill</th>
+                        <td>Smarts</td>
+                        <td>Dex, acrobat</td>
+                        <td>Super speed</td>
+                        <td>Super speed</td>
+                    </tr>
+                </table>
+            </p>
+
+            <p>
+                <figure>
+                    <!-- url --><img src="http://localhost/test.png" />
+                    <caption>Lorem ipsum</caption>
+                </figure>
+            </p>
+        </article>
+
+        <aside>
+            <header>
+                <h1>Lorem Ipsum</h1>
+            </header>
+
+            <p>
+                Lorem ipsum dolor sit amet consectetur adipisicing elit. Tempore cum, blanditiis a minima aspernatur
+                corporis pariatur, perferendis explicabo consectetur tenetur iste, fuga possimus corrupti dolorem
+                laudantium sapiente sunt error autem.
+            </p>
+
+            <figure>
+                <!-- entity --><img src="embed:Eduardokum\LaravelMailAutoEmbed\Tests\fixtures\PictureEntity:1" />
+                <caption>Lorem Ipsum</caption>
+            </figure>
+        </aside>
+    </main>
+</body>
+
+</html>
diff --git a/tests/lib/formats/html5-valid.html b/tests/lib/formats/html5-valid.html
new file mode 100644
index 0000000..782c7a1
--- /dev/null
+++ b/tests/lib/formats/html5-valid.html
@@ -0,0 +1,45 @@
+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+    <meta charset="utf-8">
+</head>
+
+<body>
+    <main>
+        <article>
+            <h1>Lorem Ipsum</h1>
+
+            <p>
+                Lorem ipsum dolor sit amet consectetur adipisicing elit. Nulla, dolorum assumenda aliquam blanditiis,
+                necessitatibus mollitia delectus sapiente amet earum minima qui non deserunt quidem, doloremque
+                architecto voluptatem eveniet illo aperiam.
+            </p>
+
+
+            <figure>
+                <!-- url --><img src="http://localhost/test.png" />
+                <caption>Lorem ipsum</caption>
+            </figure>
+        </article>
+
+        <aside>
+            <header>
+                <h1>Lorem Ipsum</h1>
+            </header>
+
+            <p>
+                Lorem ipsum dolor sit amet consectetur adipisicing elit. Tempore cum, blanditiis a minima aspernatur
+                corporis pariatur, perferendis explicabo consectetur tenetur iste, fuga possimus corrupti dolorem
+                laudantium sapiente sunt error autem.
+            </p>
+
+            <figure>
+                <!-- entity --><img src="embed:Eduardokum\LaravelMailAutoEmbed\Tests\fixtures\PictureEntity:1" />
+                <caption>Lorem Ipsum</caption>
+            </figure>
+        </aside>
+    </main>
+</body>
+
+</html>