For Gmail users overwhelmed by inbox clutter, the great Gmail redesign of 2013 may have been just the thing, hiding promotional e-mails and social network updates behind tabs. The companies sending those promotional e-mails, on the other hand, are less than thrilled with the change. However, the change may not be as bad as they fear. “With what we’re seeing right now, it’s not a game changer,” says Jason Warnock, vice president of market intelligence at Yesmail. A Google spokeswoman says the new inbox was designed to help users organize their mail; happy users are good for Google. Here’s what else is good for Google: more advertising. And while sending out 500,000 e-mail promotions is more or less free, the other options for reaching Gmail users - namely, buying adjacent ads - are not. If the new format drives just a fraction of companies to take that step, the returns could be handsome for Google