Gmail的IMAP服务器显示“系统错误（失败）”

Question

我正在开发一个应用程序，我需要的是复制邮件“草稿”到“发送”文件夹，但有时gmail说

A5 NO System Error (Failure)
Jan 10, 2014 6:52:48 AM com.google.code.samples.xoauth.ChangeLabelXAuth changeMa                      ilLabel
WARNING: Exception:A5 NO System Error (Failure)
com.google.code.javax.mail.MessagingException: A5 NO System Error (Failure);
  nested exception is:
        com.google.code.com.sun.mail.iap.CommandFailedException: A5 NO System Er                      ror (Failure)
        at com.google.code.com.sun.mail.imap.IMAPFolder.copyMessages(IMAPFolder.                      java:1629)
        at com.google.code.samples.xoauth.ChangeLabelXAuth.changeMailLabel(Chang                      eLabelXAuth.java:111)
        at com.zeronebyte.unsendme.service.UserMailServiceImpl.changeLabel(UserM                      ailServiceImpl.java:173)
        at com.pericent.gdataClient.ScheduleTaskAtTime.doGet(ScheduleTaskAtTime.                      java:74)