Images are not displayed in the email from a page shared inline in the message

Steps to reproduce

1. Have the Mail Sending section from Administration configured (I've tested with a real Gmail account, Web version)
2. Go to a page containing an image (or create one by using the Encyclopedia template)
3. On the page, click 'More Actions' > 'Share by Email'
4. From 'Include the current page' section, select 'Inline in the message'
5. Click 'Send' button
6. Go to the received email and observe the content displayed

Expected results

All images from the page are also displayed in the received email

Actual results

No image is displayed, only the name of the images are displayed instead.

The issue was reproduced as well on XWiki 15.10.16, but it's probably older.