Sometimes an email service provider can make a mistake, and the service provider's customers might not get email under certain circumstances through no fault of their own. I would surmise that this probably isn't that common, but in the interest of giving someone the benefit of the doubt, it is possible--hence my recommendation to try to contact the vendor using other means, if possible, before being 100% certain they're ignoring you.That is absolutely inexcusable with regard to a business, be it big OR small!