您好：
这个警告通知在30天后被托管文件夹助理删除， 因为它在同步系统通知系统中被标记为保留的标记。
您可以参考一下这个帖子。
https://social.technet.microsoft.com/Forums/exchange/en-US/b2f2d366-e8bb-4b8e-80da-a08b4c8e84e5/exchange2013-eac-clear-alertsnotifications?forum=exchangesvrgeneral
另外，建议您可以到我们exchange server的论坛去寻求支持
https://social.technet.microsoft.com/Forums/exchange/en-US/home?category=exchangeserver
Best Regards,
Mary Dong
Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.
