diff --git a/lib/classes/StudipMail.class.php b/lib/classes/StudipMail.class.php
index db68a110378973a69481e0f7b229b4efaa80392b..4974f660260705314cc8570b7c0a139b691e27ed 100644
--- a/lib/classes/StudipMail.class.php
+++ b/lib/classes/StudipMail.class.php
@@ -35,6 +35,11 @@ class StudipMail
      * @var array
      */
     private $attachments = [];
+    /**
+     * Array of attachments that are related to the content
+     * @var array
+     */
+    private $related_attachments = [];
     /**
      * @var array
      */
@@ -307,6 +312,17 @@ class StudipMail
         return $this;
     }
 
+    public function addRelatedAttachment(string $file_name, string $name, string $type, string $content_id): void
+    {
+        $this->related_attachments[$name] = [
+            'FileName' => $file_name,
+            'Name' => $name,
+            'Content-Type' => $type,
+            'Disposition' => 'inline',
+            'Content-ID' => $content_id
+        ];
+    }
+
     /**
      * @param $name
      * @return StudipMail provides fluent interface
@@ -411,16 +427,29 @@ class StudipMail
             $transporter->SetMultipleEncodedEmailHeader($type, $recipients);
         }
         $transporter->SetEncodedHeader('Subject', $this->getSubject());
-        if($this->getBodyHtml()){
-            $html_part = '';
+        if($this->getBodyHtml()) {
+            $html_part = 0;
             $transporter->CreateQuotedPrintableHTMLPart($this->getBodyHtml(), "", $html_part);
             $text_part = '';
             $text_message = $this->getBodyText();
+
             if(!$text_message){
                 $text_message = _('Diese Nachricht ist im HTML-Format verfasst. Sie benötigen eine E-Mail-Anwendung, die das HTML-Format anzeigen kann.');
             }
             $transporter->CreateQuotedPrintableTextPart($transporter->WrapText($text_message), "", $text_part);
+
             $part = [$text_part, $html_part];
+            if (count($this->related_attachments) > 0) {
+                $relparts = [$html_part];
+                $i = 99;
+                $multipart = 0;
+                foreach ($this->related_attachments as $one) {
+                    $transporter->CreateFilePart($one, $i);
+                    $relparts[] = $i;
+                }
+                $transporter->CreateRelatedMultipart($relparts, $multipart);
+                $part = [$text_part, $multipart];
+            }
             $transporter->AddAlternativeMultipart($part);
         } else {
             $transporter->AddQuotedPrintableTextPart($this->getBodyText());
diff --git a/lib/messaging.inc.php b/lib/messaging.inc.php
index 0fb7c3fd47c3c648bf337f53276816c00b99a474..8df15ba9ae967660edd8ead4df52c4280e655554 100644
--- a/lib/messaging.inc.php
+++ b/lib/messaging.inc.php
@@ -229,6 +229,15 @@ class messaging
         $mail->setSubject($title)
             ->addRecipient($to, $rec_fullname)
             ->setBodyText($mailmessage);
+
+        // Add Stud.IP logo as "pseudo" attachment - this will be embedded in the mail via Content-ID.
+        $mail->addRelatedAttachment(
+            $GLOBALS['STUDIP_BASE_PATH'] . '/public/assets/images/logos/studip4-logo@2x.png',
+            'studip-logo.png',
+            'image/png',
+            'studiplogo'
+        );
+
         if (mb_strlen($reply_to)) {
             if ($GLOBALS['MESSAGING_FORWARD_USE_REPLYTO']) {
                 $mail->setReplyToEmail($reply_to)
diff --git a/templates/mail/html.php b/templates/mail/html.php
index cfb4e95fc724fe9e51caefe2ad5447afd9190655..1987333a15e7451e0e3c1cb4a3749a4927cdc803 100644
--- a/templates/mail/html.php
+++ b/templates/mail/html.php
@@ -11,9 +11,11 @@
 <html>
     <head>
         <style>
-            body {
+            html {
                 background-color: #e7ebf1;
                 font-family: 'Lato', Helvetica, Arial, sans-serif;
+                height: 100%;
+                width: 100%;
             }
 
             a, a:link, a:visited {
@@ -42,20 +44,25 @@
 
             .studip-mail header {
                 border-bottom: 1px solid #d0d7e3;
+                display: block;
                 text-align: center;
                 padding-bottom: 15px;
             }
 
-            .studip-mail-header-logo {
+            .studip-mail header .studip-mail-header-logo {
                 margin-left: auto;
                 margin-right: auto;
+                width: 100%;
             }
 
-            .studip-mail-sndrec {
+            .studip-mail header .studip-mail-sndrec {
+                margin-left: auto;
+                margin-right: auto;
                 margin-top: 0;
+                width: 100%;
             }
 
-            .studip-mail-message {
+            .studip-mail .studip-mail-message {
                 line-height: 1.33;
                 padding: 15px 25px;
             }
@@ -63,7 +70,10 @@
             .studip-mail footer {
                 border-top: 1px solid #d0d7e3;
                 text-align: center;
+                margin-left: auto;
+                margin-right: auto;
                 padding-top: 15px;
+                width: 100%;
             }
         </style>
     </head>
@@ -71,7 +81,7 @@
         <article class="studip-mail">
             <header>
                 <div class="studip-mail-header-logo" >
-                    <img alt="" width="130" height="92" src="data:image/svg+xml;base64,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">
+                    <img alt="" width="130" height="92" src="cid:studiplogo">
                 </div>
                 <p class="studip-mail-sndrec">
                     <?php if ($snd_fullname) : ?>
diff --git a/templates/mail/notification_html.php b/templates/mail/notification_html.php
index d046cb298ae33f5cc70a7eb441af4bd18b8d8942..4502ae5e7004c5de83da3c30e91381bc42931a6e 100644
--- a/templates/mail/notification_html.php
+++ b/templates/mail/notification_html.php
@@ -10,9 +10,11 @@
 <html>
     <head>
         <style>
-            body {
+            html {
                 background-color: #e7ebf1;
                 font-family: 'Lato', Helvetica, Arial, sans-serif;
+                height: 100%;
+                width: 100%;
             }
 
             a, a:link, a:visited {
@@ -41,20 +43,25 @@
 
             .studip-mail header {
                 border-bottom: 1px solid #d0d7e3;
+                display: block;
                 text-align: center;
                 padding-bottom: 15px;
             }
 
-            .studip-mail-header-logo {
+            .studip-mail header .studip-mail-header-logo {
                 margin-left: auto;
                 margin-right: auto;
+                width: 100%;
             }
 
-            .studip-mail-sndrec {
+            .studip-mail header .studip-mail-sndrec {
+                margin-left: auto;
+                margin-right: auto;
                 margin-top: 0;
+                width: 100%;
             }
 
-            .studip-mail-message {
+            .studip-mail .studip-mail-message {
                 line-height: 1.33;
                 padding: 15px 25px;
             }
@@ -62,7 +69,10 @@
             .studip-mail footer {
                 border-top: 1px solid #d0d7e3;
                 text-align: center;
+                margin-left: auto;
+                margin-right: auto;
                 padding-top: 15px;
+                width: 100%;
             }
         </style>
     </head>
@@ -70,7 +80,7 @@
     <article class="studip-mail">
         <header>
             <div class="studip-mail-header-logo" >
-                <img alt="" width="130" height="92" src="data:image/svg+xml;base64,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">
+                <img alt="" width="130" height="92" src="cid:studiplogo">
             </div>
             <p class="studip-mail-sndrec">
                 <?= sprintf(
diff --git a/vendor/email_message/email_message.php b/vendor/email_message/email_message.php
index dcef90c2ae51f51c6a54dc7d51b927e378e403bb..a94e9961a83ec8e0bb0bac00169516ac2908b9a7 100644
--- a/vendor/email_message/email_message.php
+++ b/vendor/email_message/email_message.php
@@ -2608,6 +2608,9 @@ class email_message_class
 		if(IsSet($file['Cache'])
 		&& $file['Cache'])
 			$definition['Cache'] = 1;
+		if(IsSet($file['Content-ID'])
+		&& $file['Content-ID'])
+			$definition['Content-ID'] = $file['Content-ID'];
 		return("");
 	}