it's both good and bad news for a marketer, depending on what and how you are measuring.
Previously GMail disabled images to be opened by default. That meant only about 4% of marketing emails were able to be recorded as 'opened' via the tracking tag - IE ONly about 4% of people said "Show me the images"
but.... for those 4% you could tell each and every time they opened the emails - Multi opens.
Those numbers were very stable and allowed a marketer to use the 4% as a guide alongside further known metrics (click throughs, sales etc) and project accordingly.
Now though as all images will be shown by default, every unique image, will be called at least once upon open. That means that 100% of the open rate can be recorded. The downside is that the image will then be cached by Google so multi opens won't then be recorded.
On top of that that, you wont be able to see what images are called from where, using what browsers etc etc - IE Normal log file analysis etc will break as all images will be called from Google's proxy with their (incorrect) proxy User Agent, IP etc.
so... this update is a bag of good news and bad news, depending on what you measure and how you measure it.
