Newbe Dev Stack

Answer : I didn't try Matthew's solution but it seems the safer solution to try first. If that doesn't work though, I deleted the entire conversation from the outbox , having given up on trying to keep the conversation. I was surprised to find that this only deleted the queued message. The rest of the conversation stayed intact in my inbox. One way would be to clear the data for Gmail via the Settings app.

Answer : base64 encoded images are not well supported in email. They aren't supported in most web email clients (including Gmail) and are completely blocked in Outlook. Apple Mail is one of the few clients that does support them, that's why you're able to see them there but not elsewhere. Another thing to be mindful of with base64 encoded images is email file size. Gmail App (iOS, Android) and Outlook (iOS) truncate email messages whose file size exceeds 102KB. Remotely referenced images (Eg. <img src="http://www.website.com/image.png"> do not count towards the email's file size, but base64 encoded images do and can quickly blow out an email's file size past the 102KB limit. Just something else to consider. It looks like that direct encoded images (non-bease64 ) are also not supported by gmail :( - I write below snippet to convert image from base64 to direct form and send it in email - but still not see any image :( . To solve this issue ...