Create HTML Mail with inline Image and PDF Attachment
<p>I want to write a HTML mail in Python/Django containing these parts:</p>

<ul>
<li>HTML linking to logo.png</li>
<li>logo.png which should be displayed inline (not as attachment) in the mail user agent</li>
<li>info.pdf which should be displayed as attachment</li>
<li>Text which should be displayed if the mail user agent can't display HTML.</li>
</ul>

<p>I followed <a href="https://www.vlent.nl/weblog/2014/01/15/sending-emails-with-embedded-images-in-django/" rel="nofollow noreferrer">this</a> blog post.</p>

<p>Result:</p>

<ul>
<li>The HTML and the inline image works</li>
<li>but the info.pdf file gets treated like the inline logo.png, and some mail user agent don't show it :-(</li>
</ul>

<p>How to create both ways (download (info.pdf) and inline (logo.png)) in one mail in python?</p>