diff --git a/modules/system/ServiceProvider.php b/modules/system/ServiceProvider.php
index 1bc573b359..d8e21c4eec 100644
--- a/modules/system/ServiceProvider.php
+++ b/modules/system/ServiceProvider.php
@@ -357,9 +357,7 @@ protected function registerMailer()
          * Override standard Mailer content with template
          */
         Event::listen('mailer.beforeAddContent', function ($mailer, $message, $view, $data, $raw, $plain) {
-            $method = $raw === null ? 'addContentToMailer' : 'addRawContentToMailer';
-            $plainOnly = $view === null; // When "plain-text only" email is sent, $view is null, this sets the flag appropriately
-            return !MailManager::instance()->$method($message, $raw ?: $view ?: $plain, $data, $plainOnly);
+            return !MailManager::instance()->addContent($message, $view, $plain, $raw, $data);
         });
     }
 
diff --git a/modules/system/classes/MailManager.php b/modules/system/classes/MailManager.php
index b11fee91cb..08e8a10c41 100644
--- a/modules/system/classes/MailManager.php
+++ b/modules/system/classes/MailManager.php
@@ -52,14 +52,15 @@ class MailManager
      * Same as `addContentToMailer` except with raw content.
      *
      * @return bool
+     *
+     * @deprecated Use addContent() instead
      */
     public function addRawContentToMailer($message, $content, $data)
     {
-        $template = new MailTemplate;
-
-        $template->fillFromContent($content);
+        $text = new MailTemplate;
+        $text->fillFromContent($content);
 
-        $this->addContentToMailerInternal($message, $template, $data);
+        $this->addContentToMailerInternal($message, null, $text, $data);
 
         return true;
     }
@@ -73,6 +74,8 @@ public function addRawContentToMailer($message, $content, $data)
      * @param array $data
      * @param bool $plainOnly Add only plain text content to the message
      * @return bool
+     *
+     * @deprecated Use addContent() instead
      */
     public function addContentToMailer($message, $code, $data, $plainOnly = false)
     {
@@ -92,21 +95,75 @@ public function addContentToMailer($message, $code, $data, $plainOnly = false)
             return false;
         }
 
-        $this->addContentToMailerInternal($message, $template, $data, $plainOnly);
+        $html = $text = $template;
+
+        if ($plainOnly) {
+            $html = null;
+        }
+        $this->addContentToMailerInternal($message, $html, $text, $data);
 
         return true;
     }
 
     /**
-     * Internal method used to share logic between `addRawContentToMailer` and `addContentToMailer`
+     * Restore proper behavior in-line with Laravel Mailer
+     * Replaces both `addContentToMailer` and `addRawContentToMailer`
      *
      * @param \Illuminate\Mail\Message $message
-     * @param string $template
+     * @param string|null $view
+     * @param string|null $plain
+     * @param string|null $raw
+     * @param array $data
+     * @return bool
+     */
+    public function addContent($message, $view = null, $plain = null, $raw = null, $data = [])
+    {
+        $html = $text = null;
+
+        // We only handle mail template names as a string, let the caller handle the content if we receive anything else
+
+        if (is_string($view)) {
+            if (isset($this->templateCache[$view])) {
+                $html = $this->templateCache[$view];
+            } else {
+                $this->templateCache[$view] = $html = MailTemplate::findOrMakeTemplate($view);
+            }
+        }
+
+        if (is_string($plain)) {
+            if (isset($this->templateCache[$plain])) {
+                $text = $this->templateCache[$plain];
+            } else {
+                $this->templateCache[$plain] = $text = MailTemplate::findOrMakeTemplate($plain);
+            }
+        }
+
+        // raw content will overwrite plain view content, as done in laravel
+        if (is_string($raw)) {
+            $text = new MailTemplate;
+            $text->fillFromContent($raw);
+        }
+
+        // bailout if we have no content
+        if (is_null($html) && is_null($text)) {
+            return false;
+        }
+
+        $this->addContentToMailerInternal($message, $html, $text, $data);
+
+        return true;
+    }
+
+    /**
+     * Internal method used to share logic between `addContent`, `addRawContentToMailer` and `addContentToMailer`
+     *
+     * @param \Illuminate\Mail\Message $message
+     * @param MailTemplate|null $html
+     * @param MailTemplate|null $text
      * @param array $data
-     * @param bool $plainOnly Add only plain text content to the message
      * @return void
      */
-    protected function addContentToMailerInternal($message, $template, $data, $plainOnly = false)
+    protected function addContentToMailerInternal($message, $html = null, $text = null, array $data = [])
     {
         /*
          * Inject global view variables
@@ -122,28 +179,39 @@ protected function addContentToMailerInternal($message, $template, $data, $plain
         $symfonyMessage = $message->getSymfonyMessage();
 
         if (empty($symfonyMessage->getSubject())) {
-            $message->subject($this->renderTwig($template->subject, $data));
+            if ($html) {
+                $message->subject($this->renderTwig($html->subject, $data));
+            } else if ($text) {
+                $message->subject($this->renderTwig($text->subject, $data));
+            }
         }
 
         $data += [
             'subject' => $symfonyMessage->getSubject()
         ];
 
-        if (!$plainOnly) {
-            /*
-             * HTML contents
-             */
-            $html = $this->renderTemplate($template, $data);
-
-            $message->html($html);
+        /*
+         * HTML content
+         */
+        if ($html) {
+            $message->setBody($this->renderTemplate($html, $data), 'text/html');
+            if (!$text && $html->content_text) {
+                $text = $html;
+            }
         }
 
         /*
-         * Text contents
+         * Text content
          */
-        $text = $this->renderTextTemplate($template, $data);
+        if ($text) {
+            $method = $html ? 'addPart' : 'setBody';
+            $message->{$method}($this->renderTextTemplate($text, $data), 'text/plain');
+        }
 
-        $message->text($text);
+        /*
+         * End twig transaction
+         */
+        $this->stopTwig();
     }
 
     //
diff --git a/tests/unit/system/classes/MailManagerTest.php b/tests/unit/system/classes/MailManagerTest.php
new file mode 100644
index 0000000000..364cb47402
--- /dev/null
+++ b/tests/unit/system/classes/MailManagerTest.php
@@ -0,0 +1,112 @@
+<?php
+
+use Illuminate\Mail\Message;
+use System\Classes\MailManager;
+use System\Models\MailTemplate;
+use Symfony\Component\Mime\Email;
+use Symfony\Component\Mime\Part\TextPart;
+
+class MailManagerTest extends PluginTestCase
+{
+
+    public function setUp() : void
+    {
+        parent::setUp();
+
+        $this->message = new Message(new Email());
+
+        foreach (['html', 'plain'] as $view) {
+            $t = new MailTemplate();
+            $t->is_custom = true;
+            $t->code = "$view-view";
+            $t->subject = "$view view [{{ mode }}]";
+            $t->content_html = "my $view view content";
+            $t->description = "my $view view description";
+            $t->save();
+        }
+    }
+
+    //
+    // Tests
+    //
+
+    public function testAddContent_Html()
+    {
+        $plain = $raw = null;
+        $html = new TextPart('html-view', $subtype="html");
+        $data = ['mode' => 'test'];
+
+        $result = MailManager::instance()->addContent($this->message, $html, $plain, $raw, $data);
+        $symfonyMessage = $this->message->getSymfonyMessage();
+
+        $this->assertEquals($html, $symfonyMessage->getHtmlBody());
+        $this->assertEquals('html view [test]', $symfonyMessage->getSubject());
+    }
+
+    public function testAddContent_Plain()
+    {
+        $html = $raw = null;
+        $plain = new TextPart('plain-view');
+        $data = ['mode' => 'test'];
+
+        $result = MailManager::instance()->addContent($this->message, $html, $plain, $raw, $data);
+        $symfonyMessage = $this->message->getSymfonyMessage();
+
+        $this->assertTrue($result);
+        $this->assertEquals($plain, $symfonyMessage->getTextBody());
+        $this->assertEquals('plain view [test]', $symfonyMessage->getSubject());
+    }
+
+    public function testAddContent_Raw()
+    {
+        $html = $plain = null;
+        $raw = new TextPart('my raw content');
+        $data = ['mode' => 'test'];
+
+        $result = MailManager::instance()->addContent($this->message, $html, $plain, $raw, $data);
+        $symfonyMessage = $this->message->getSymfonyMessage();
+
+        $this->assertTrue($result);
+        $this->assertEquals('No subject', $symfonyMessage->getSubject());
+        $this->assertEquals($raw, $symfonyMessage->getBody());
+    }
+
+    public function testAddContent_Html_Plain()
+    {
+        $raw = null;
+        $html = new TextPart('html-view', $subtype="html");
+        $plain = new TextPart('plain-view');
+        $data = ['mode' => 'test'];
+
+        $result = MailManager::instance()->addContent($this->message, $html, $plain, $raw, $data);
+        $symfonyMessage = $this->message->getSymfonyMessage();
+        $parts = $symfonyMessage->getAttachments();
+
+        $this->assertTrue($result);
+        $this->assertEquals('html view [test]', $symfonyMessage->getSubject());
+        $this->assertEquals($html, $symfonyMessage->getHtmlBody());
+
+        $this->assertEquals(1, count($parts));
+        $this->assertEquals($plain, $symfonyMessage->getTextBody());
+    }
+
+    public function testAddContent_Html_Plain_Raw()
+    {
+        $html = new TextPart('html-view', $subtype="html");
+        $plain = new TextPart('plain-view');
+        $raw = new TextPart('my raw content');
+        $data = ['mode' => 'test'];
+
+        $result = MailManager::instance()->addContent($this->message, $html, $plain, $raw, $data);
+        $symfonyMessage = $this->message->getSymfonyMessage();
+        $parts = $symfonyMessage->getAttachments();
+
+        $this->assertTrue($result);
+        $this->assertEquals('html view [test]', $symfonyMessage->getSubject());
+        $this->assertEquals($html, $symfonyMessage->getHtmlBody());
+
+        $this->assertEquals(1, count($parts));
+        $this->assertEquals($plain, $symfonyMessage->getTextBody());
+        $this->assertEquals($raw, $symfonyMessage->getBody());
+    }
+}