Labor leaders see e-mail-based organizing as a way to reverse labor’s declining membership. Why? It’s fast, cheap and relatively private. More unions are launching membership drives online, reaching your employees on their company-owned PCs through their company-owned e-mail accounts. You cannot censor all e-mail that your employees receive, but you can monitor it vigilantly and alert workers that their e-mail is not private. The National Labor Relations Board plans to rule on whether union organizing by e-mail is legal. It appears likely that unions will have at least some leeway to continue the practice.