How can I send a message to SEP client

In our SEPM 12.1.2015.2015, some unknown client can connect back to SEPM, but we cannot find the owner by last logon user or IP or computer name. Can I trigger/send a message to this SEP client and notify them to contact us, so that we will know who is the owner of this client?

Seems only when risk found or definition is outdated(over 7 days), there will be customized notification can be sent to client. But these clients is up-to-date

Thanks