Sep 2017 - EA DomainKeys/DKIM for IIS SMTP Service and Exchange Server 3.5 released

Inbound DKIM/SPF/DMARC authentication;
Fix bad headers in embedded message automatically;
New kernel with performance improvement.

An inbound transport agent for DKIM/SPF/DMARC authentication is provided as an optional component. You can use the authentication/verification result to filter the spoofing emails to spam folder, or even you can use it to reject the email in SMTP service directly.

To learn more detail, please refer to this tutorial:
DKIM/SPF/DMARC Inbound Authentication

https://www.emailarchitect.net/domainkeys/kb/dkim_exchange_inbound.aspx