In short, because HTML is far easier to generate.

Tim, why not generate a PDF file instead of the HTML file?

That's probably exactly what it's doing. It doesn't make sense to just arbitrarily remove all embedded images from emails so there might be a setting somewhere you can adjust.

Hi Tim

There is indeed an issue with viewing the html file directly from an email. It strips the embedded source and changes/removes tags unnecessarily. However, if you download the file to your desktop and then open it in your browser (chrome or IE), it displays fine.

Really strange. Its as if the email client is seeing something it doesn't like and removes it to protect the user in case it might be malicious.

Huehnerstall that is incorrect. iOS has no problem displaying HTML with embedded images. The PLOG is a good example of this.

plume_tray we've just tested this again, sending a route from an iPad, and the HTML generated works fine. It includes an <img> tag with embedded source. I have no idea what could be stripping this from the email you receive, but I would suspect your email client is doing it. I've uploaded the file so you can see what it looks like:
http://www.skydemon.aero/extras/wb.html

To clarify, I am using the "Send by Email" feature on the iPad.

Opening the email and the attached file, it doesn't show the envelope. I have tried both IE 11 and Chrome v39 on a Windows Laptop. Its seems as though the iPad app isn't sending the envelope in the attachment.

Here's a snippet of the HTML from the attachment. There is an img tag but the source image isn't there.

[code]
</table>
<p>The graph below illustrates the acceptable loading envelope of the aircraft.</p><p><img style="max-width:140mm" border="0"></p>
</p></div>
</body></html>
[/code]

Where are you viewing the HTML file? The graph should certainly be embedded; a quick test sending an email to myself shows it when I view the HTML file in Internet Explorer.

The Weight and Balance Calculations.html file produced by the "Send By Email" feature doesn't display the CG envelope.

I'm using SD v3.2.0 on IPad Mini IOS 7.1.2

The following line at the bottom of the file implies there should be:

"The graph below illustrates the acceptable loading envelope of the aircraft."

Thanks