SPF (Sender Policy Framework) is used by Office 365 to filter incoming messages. And once you are using Office 365 you already have included something like spf.protection.outlook.com to your domain records. The record confirms that Microsoft can send messages on your behalf.
And since Xink ReRouter servers push messages back to Office 365 after processing, they should be allowed to do it smoothly. So, if you are experiencing any false positive spam detection issues, add the following statement to your domain(s) SPF record:
So the whole record would look like this: "v=spf1 mx include:spf.protection.outlook.com include:spfrerouting.xink.io ~all"
Please note that spfrerouting.xink.io includes soft fail option, if it is no acceptable in your case, just add our IP addresses directly. 184.108.40.206 for US data center and 220.127.116.11 for EU data center.
Sample record: "v=spf1 mx include:spf.protection.outlook.com ip4:18.104.22.168 -all"