Policy tips don't work in Outlook for some types of policy
The documentation on policy tips states that the following tips are not currently supported in Outlook 2013 and beyond:
We're currently working on support for showing policy tips for additional conditions. These include:
Any email attachment's content could not be scanned
Any email attachment's content didn't complete scanning
Attachment file extension is
Attachment is password protected
Document property is
Recipient domain is
Sender IP address is
Support for these tips needs to be added, as this makes the policy much less useful (for example, you can't set an "advisory" policy that attachments shouldn't be sent outside the domain as there is no way for someone to override and provide a business case without the policy tip).
Vlk, Petr (KPCS CZ) commented
We now have Outlook 2019 and the situation is basically the same.