Is Google Playing Fair With Groupon, et al?

An anonymous reader writes with the claim (illustrated with what seems like damning screen-shot evidence) that "Google is using Gmail's priority inbox to give special treatment to its own daily deal emails over all the rest."

Re:wow

[AlexBirch]

or slashdot / blog presenting bad evidence in order to get more views?
Groupon is still marked as important for my gmail account.

Re:Non-story

[Skuld-Chan]

I'd say it raises alarms because google offers doesn't do that on my email inbox...

Re:Non-story

[Mistlefoot]

Definitly.

A reply on the original article is

"Isaac said...

        Google knows that you signed up for Google Offers because it's your own account.

        They don't know the same thing about other daily offer emails because they do not have access to those other site's subscription information, and all these emails look like spam. So without that additional information available, how can Google tell the difference between spam/semi-spam and things that you sign up for? It can't, until you tell it they are important."