var r = /^((([a-z0-9_.-]+)@([da-z.-]+).([a-z.]{2,6};))*(([a-z0-9_.-]+)@([da-z.-]+).([a-z.]{2,6})))$/
var str = 'xxxx@126.com;123234234@qq.com;xxxxx@xxxxx.con.cn';if (r.test(str))