Sending image in email with smtp notification; Gmail app on Android does not show image

Hi all,

I made a notify automation which sends me an email with an inline image of our doorbell when someone rings the door. This works and when watching the mail in Outlook on a Mac, the inline picture is shown. When however looking at the mail in the Android Gmail app, the picture is not shown and only the alt line is shown.

Does someone know how to create a html email which shows inline pictures on the Android Gmail app?

This is what I have now:

My notify configuration in configuration.yaml:

  - name: mail_trle
    platform: smtp
    sender: [email protected]
    recipient: [email protected]
    port: 587
    timeout: 30
    username: [email protected]
    password: XXX
    encryption: starttls
    sender_name: Home Assistant

The automation:

alias: "Email notificatie: deurbel wordt ingedrukt"
description: Stuur email wanneer de deurbel wordt ingedrukt
  - platform: device
    device_id: 1b4d7c2c6725257c50bb3a8d4a69a48f
    domain: nest
    type: doorbell_chime
condition: []
  - service: camera.snapshot
      filename: /config/www/tmp/deurbel.jpg
      entity_id: camera.voordeur
  - delay:
      hours: 0
      minutes: 0
      seconds: 5
      milliseconds: 0
  - service: notify.mail_trle
      message: Er heeft iemand op de deurbel gedrukt.
      title: Er stond iemand voor de deur!
          - /config/www/tmp/deurbel.jpg
        html: >
          <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
          ""> <html
          lang="en" xmlns="">
                  <meta charset="UTF-8">
                  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
                  <meta name="viewport" content="width=device-width, initial-scale=1.0">
                  <title>Intruder alert</title>
                  <link rel="stylesheet" href="">
                  <link rel="stylesheet" href="">
                  <style type="text/css">
                      @font-face {
                        font-family: 'Open Sans';
                        font-style: normal;
                        font-weight: 300;
                        src: local('Open Sans Light'), local('OpenSans-Light'), url( format('truetype');
                      h1,h2,h3,h4,h5,h6 {
                          font-family:'Open Sans',Arial,sans-serif;
                          margin:10px 0
                <div class="jumbotron jumbotron-fluid" style="background-color: #f00a2d; color: white;">
                    <div class="container py-0">
                        <h2>Er staat iemand bij de voordeur!!</h2>
                  <center><p>Iemand heeft zojuist op de deurbel gedrukt. Een foto van de persoon zie je hieronder.</p>
                  <p>Groeten van Home Assistant</p></center>
                <div class="container-fluid">
                  <div class="row">
                    <div class="col-xs-12 col-md-6 px-0">
                      <center><img src="cid:deurbel.jpg" class="rounded" style="width: 50%;" alt="Foto gemaakt door de deurbel." /></center>
              <script src=""></script>
              <script src=""></script>
mode: single

Thank you!

This is how the mail looks in the Gmail app on my Android phone: