(FORTUNE Small Business) – Chain e-mails offering massive rebates or touting corporate conspiracies can do more than clog your in-box. Ask Michael Coles, CEO of Caribou Coffee, based in Minneapolis, who has spent the past few months debunking rumors, spread through e-mail and the Internet, that his company has ties to Islamic terrorism. Caribou ignored the chatter for nearly two years. Then sales, which run $120 million a year, fell by 35% at stores in some Jewish neighborhoods around Chicago and Detroit. Coles, 60, parachuted in and impressed upon rabbis that while Caribou is majority-owned by the First Islamic Investment Bank of Bahrain, the alleged connection to Muslim radicals is bogus—and that Coles is Jewish. — BRANDON COPPLE