java.awt.HeadlessException
        at java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:159)
        at java.awt.List.<init>(List.java:216)
        at java.awt.List.<init>(List.java:171)
        at com.mail.MailSendWork.<init>(MailSendWork.java:40)
        at com.mail.MailWorker.run(MailWorker.java:30)
        at edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1061)
        at edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:575)
        at java.lang.Thread.run(Thread.java:595)

在环境变量中加入 export DISPLAY=localhost:0 再次执行 ，OK！