Email phishing scams are flooding the Internet: How not to get lured in.

Nearly 85 percent of American and British organizations have been victims of phishing attacks, most delivered by email (other popular vehicles include mobile devices, social media, and phone calls).

Financial loss, productivity slowdown, and reputation damage are just some of the consequences companies like Seagate, Snapchat, and (ironically) the web-security company KnowBe4 have suffered after a strike.

Schools are juicy prey, too. And all it takes is one—just ...