An anonymous reader writes "MozillaZine reports that the Mozilla Foundation is cracking down on those selling unofficial Mozilla-branded merchandise. This takes the form of an open letter addressed to retailers of goods that bear the Mozilla name or logos. The letter suggests that the Foundation are willing to work with those selling Mozilla wares, as long as they get a cut and the retailer isn't operating in the US, Canada or Mexico, where they would be competing with the Foundation's own Mozilla Store. Threats of legal action for non-compliance are issued, albeit with friendly overtones. This open letter is part of the Mozilla Foundation's campaign to better enforce its trademarks, an effort that began when the Foundation was launched in July. In a related move, the Foundation announced that the new Firefox artwork is not open-source and can only be used in official builds or those sanctioned by the Foundation - this has led to debates about whether Firefox is free enough to be included in the Debian Linux distribution."