As seen support.mozilla.org/en-US/questions/930024 and answers.microsoft.com/en-us/outlook_com/forum/oemail-osend/images-turn-to-grey-squares-in-sent-mail/734b611d-c9e1-465b-9fbe-9400edec23a1 Seems I have figured out how to "reproduce" this bug. I remeber yesterday of writing some emails and inserted inline images were viewable at the begining. The third onwards became gray square. I remember I was working between Rich text and HTML text in Outlook.com. Also, as I compose the second email and sent it, I notice that could merge first two emails. Then I made the third email which had same image from second email (the inline picture one). That's when it started bug (in the third email). Note: the second email has the inline picture and is not grey square, it is showing the real image. All emails referred are in Sent box. Both Firefox and IE can't show the inline picture third onwards. *off topic how do i insert line feed in my post ? it gets awful to read.