There is a labs feature for inserting images into an e-mail that I've used in Firefox for awhile now and it works great. I can provide a URL to the image and it appears in the sent e-mail just fine.
I had occasion to try this with Chrome last week and to my surprise, it didn't work. Now, it appeared to work just fine as I was composing as I could insert the image and it appeared in the composition, but the receiver of the e-mail said there were no images. I looked in my sent e-mails and sure enough, rather than an image there was just a blank box. I sent an e-mail to myself and the same thing happened. Just to check, I went back and did it with Firefox and it worked.
So, further inspection was required. I tried copying and pasting from the sent e-mail into an HTML editor and what do you know, the IMG tag was indeed wrong. Rather than:
A little more investigating revealed that things went wrong if I save the e-mail as a draft and go back to it so it doesn't happen only when the e-mail is sent.
Now, the URL I was using was a very long and complicated one pointing to a chart using Google Charts API. So I tried it in Chrome with a simpler URL to an image and that worked fine. So the conclusion is that Chrome somehow can't handle a long URL pointing to Google Charts but Firefox can.
I did submit a bug so we'll see what happens, but has anyone else observed this or a similar problem and have a solution? For now, I'm using Firefox when sending e-mails like this.