I have a static map image using the standard google maps url with no api key.
This appears to work for every email client, except recently for outlook.live.com.
Instead of the expected image, I get a gray jpg with "g.co/staticmaperror/key" written across it, which leads to this documentation.
I know Google limits the use to 25,000 per day for non-keyed requests. Is this simply Google recognizing the request limit for outlook.live.com? If so, why haven't I seen this behavior on other clients, such as Yahoo mail? Or how do they measure things like me opening the email in my desktop Outlook mailbox?