How to Successfully Embed Images in HTML for Display in Webmail Clients

How to successfully embed images in HTML for display in webmail clients?

simple answer?

You can't. Gmail, outlook etc will ignore base64 images.

Look at this site to learn more about this

Sample Image

So based on our results, it is clearly not worth using embedded images in your emails. All you will be doing is forcing people to download encoded images that they will not be able to view.

embedding image in html email

Try to insert it directly, this way you can insert multiple images at various locations in the email.

<img src="data:image/jpg;base64,{{base64-data-string here}}" />

And to make this post usefully for others to:
If you don't have a base64-data string, create one easily at:
http://www.motobit.com/util/base64-decoder-encoder.asp from a image file.

Email source code looks something like this, but i really cant tell you what that boundary thing is for:

 To: email@email.de
 Subject: ...
 Content-Type: multipart/related;
 boundary="------------090303020209010600070908"

This is a multi-part message in MIME format.
--------------090303020209010600070908
Content-Type: text/html; charset=ISO-8859-15
Content-Transfer-Encoding: 7bit

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>

    <meta http-equiv="content-type" content="text/html; charset=ISO-8859-15">
  </head>
  <body bgcolor="#ffffff" text="#000000">
    <img src="cid:part1.06090408.01060107" alt="Sample Image">
  </body>
</html>

--------------090303020209010600070908
Content-Type: image/png;
 name="moz-screenshot.png"
Content-Transfer-Encoding: base64
Content-ID: <part1.06090408.01060107>
Content-Disposition: inline;
 filename="moz-screenshot.png"

[base64 image data here]

--------------090303020209010600070908--

//EDIT: Oh, i just realize if you insert the first code snippet from my post to write an email with thunderbird, thunderbird automatically changes the html code to look pretty much the same as the second code in my post.

How to insert HTML (including images) in an e-mail in Outlook 2016+

The answer is very simple. In a way, it's obvious, but in another way, it's not.

The answer is that each segment of HTML code inserted has to be a complete HTML file, including the <!DOCTYPE>, <HTML> and <body> tags, not just the desired HTML code. The reason this is not obvious is because if you insert multiple code segments, each one has to be a complete HTML file, which is something you would never do when actually writing HTML. I presume that what is happening is that when Outlook detects a valid HTML file being "Inserted as Text", it strips the opening and closing <!DOCTYPE>, <HTML> and <body> tags and then inserts the code that was between them -- as HTML, not as text.

So, the solution I found was that instead of the single line of code shown in the question, I need to "Insert as Text" a file containing:

<!DOCTYPE html>
<html>
<body>
<img src="https://www.lenetek.com/blog/how-to-create-html-emails-in-outlook/images/attach_file.jpg" alt="Random online image">
</body>
</html>

When I insert that as text in my e-mail, I see the image, not the code.

In all the sources I found online that said to use "Insert as Text" to insert HTML in Outlook, none of them said it had to be a complete HTML file instead of just the desired code. So maybe this Q&A will be helpful to someone else, if I'm not the only person who had to scratch my head for a long time before thinking of that.

========================

Added details about using HTML in the e-mail:

As pointed out in the Lenetek article linked in the question, Outlook does not support all HTML tags. In particular, for embedding images, I have found:

When sending from Outlook:
Outlook does not support <figure> and <FigCaption>. I found that an image and caption placed in those tags were rendered inline, just ignoring the tags. For floating to the right margin, I found I was able to get the same results by replacing <figure> with <table> and then placing the image and its caption each inside of <TR><TD>...</TD></TR>.

When receiving in Outlook:
There are differences in how different e-mail clients interpret HTML, which is probably why some e-mails come with a link at the top for viewing the e-mail in one's browser. In particular, I've read that Outlook is not well behaved in this regard. And that was the case with my right-floated image referred to above.

After doing the "Insert as Text" trick, the image appeared correctly at the right margin in the draft e-mail in Outlook, but when it was sent, the CSS style float attribute was ignored and the table appeared by itself at the left margin with no text wrapped around it. I was able to fix this by, in the <table> tag, replacing the style attribute float: right; with the old-fashioned HTML attribute align="right". With that, the image and caption appeared correctly at the right margin when received in Outlook. I have not tested what it looks like in other e-mail clients.

How to make an image responsive in HTML email regardless of image size

Yes and no. Outlook tends to force the image to its actual size, regardless of your CSS and HTML sizings. So using images that are bigger than what you want to be displayed on your desktop version is likely to break on Outlook.

Your best bet for responsive images would be to have the images as 100% width inside a table that has max-width set. Then around this table, make conditional code for MSO that contains a set width table at the max-width size.

Example below:

<!--[if gte MSO 9]>
  <table width="640">
     <tr>
        <td>
<![endif]-->
  <table width="100%" style="max-width:640px;">
    <tr>
      <td>
        <img src="image.jpg" width="100%" />
      </td>
    </tr>
  </table>
<!--[if gte MSO 9]>
      </td>
    </tr>
  </table>
<![endif]-->

There will still be some quirks with using max-width as not all clients support it. I would view CSS compatability and make little tweaks as needed on top of the above to ensure it fits. Then test and test some more.

Send a base64 image in HTML email

Support, unfortunately, is brutal at best. Here's a post on the topic:

https://www.campaignmonitor.com/blog/email-marketing/2013/02/embedded-images-in-html-email/

And the post content:
Sample Image

How can I embed SVG into HTML in an email, so that it's visible in most/all email browsers?

SVG is not supported in many email clients. The best guide I’ve seen is on Style Campaign. It’s a short read that I vouch for (Anna is super smart!).

TL;DR: A variety of techniques will work in iOS mail clients and (amazingly) Blackberry. But Android, Outlook, and pretty much every other desktop and webmail client does not support SVG and requires a fallback.

How to Successfully Embed Images in HTML for Display in Webmail Clients