Hi Tom.

Gmail does not support images embedded as Data URIs. If you want to send emails with embedded images to Gmail users, consider attaching the image to the email and then referencing it in the HTML body. The following Stack Overflow answer provides a code example:
Embedding Image in HTML Email

Best Regards,
Nevron Support Team

Hi guys! You've been very helpful the past few weeks with our issues here regarding NRichTextEdit and output to html with images.  I've been using the latest version of the controls and they are working well.  We have one issue regarding html with images though.  When sending via email to Outlook and Thunderbird, the images appear fine.  However Gmail client apparently has problems because all you see is the html source. Here is a screenshot from my phone:


I have attached the source html.  Maybe with your expertise dealing with html you can see something that might cause Gmail to hiccup. :-)  Thanks very much!