Why can't Gmail view an image whose URL comes from google charts?

Question

Here is an image generated from google's chart API.

The url to generate the image is:

http://chart.apis.google.com/chart?chxl=0:|day|1:|installs&chxp=0,3|1,6072&chxr=0,0,6|1,0,12145&chxs=0,676767,11.833,0,lt,676767|1,676767,12.833,-0.333,lt,676767&chxt=x,y&chs=400x200&cht=lxy&chds=0,6,0,12145&chd=t:1,2,3,4,5,6|768,2850,6498,10948,12145,0&chdl=installs&chdlp=b&chls=1&chma=5,5,5,1&chtt=installs_per_day

GMail will not (cannot) display this image if it's included in an HTML email.
(e.g. generate and programatically send an email through gmail smtp, or use the gmail labs image insert feature, etc)

Why? Is that a bug? Is there something about encoding URLs for HTML used in emails that I'm missing?

Answer 1

That is indeed strange. I can confirm the behavior with the Labs feature you mentioned.

I don't know a lot about email encoding but the resulting message seems correct--you can see it in this Gist but doesn't display correctly in Gmail. When I do Inspect Element on the non-image in Gmail it appears that the <img> element has title and alt attributes but no src. Have you tried viewing it in another email client?

It certainly seems like a bug. I'd suggest bringing it up on Gmails' help forums. While GOOG itself isn't particularly responsive there you may find other people who have more insight into this issue.

A workaround that does appear to work, however, is shortening the URL beforehand. I tested it with both TinyURL and Goo.gl and it worked fine, at least when viewed in Gmail (the top message is with the full URL, the bottom is with the Goo.gl-shortened URL:

Sorry that's not a complete answer to your question, but I hope it helps.