A small bug exists in Exchange 2013 CU16 found through the test.

When I was doing a test recently, I found that the DLP policy of Exchange 2013 CU16 could not filter encrypted attachments, and if the DLP policy was set to "cannot check content", it would block normal messages (without attachments). At present, there is no solution, if there is such a need, it is recommended not to set up such a strategy for the time being. I tested the Exchange 2016 cu4 setting for this DLP policy and there was no problem.

I. Environmental information and rule configuration

My environment information is WIndows Server 2012 R2+Exchange 2013 cu16. I have created a DLP policy for email attachments that basically blocks messages when they contain content that cannot be checked. (this is to prevent users from sending unscannable attachments to bypass the DLP policy.) my policy configuration is as follows: (there are two rules, Rule 1 and Rule 2 in DLP)

When I applied this policy, I found that my normal messages (messages without attachments) were blocked by my DLP policy. The specific error reports and test emails are as follows:

1. Test the content of the email

2. The contents of the rejected letters received.