Email　networks　are　typical　social　networks.　The　research　on　virus　spreading　in　email　networks　can　improve　the　study　on　the　propagation　in　complex　networks.　Based　on　an　interactive　email　network,　this　paper　compares　the　efficiency　of　existing　immunization　strategies　with　the　betweenness-based　strategies.　The　comparison　results　show　that　the　betweenness-based　immunization　strategies　can　perform　more　efficiently　while　the　global　information　is　available.