We're getting a lot of spam from 52.100.0.0-52.103.255.255 IP addresses. Microsoft is currently having problems with spammers. It would be nice if we could deactivate this range from Greylist Filters. It is an internal / default greylist filter.

From SmarterMail help: "Note: Some greylist filters are included by default and cannot be modified or removed. These default filters are indicated in the grid by having a checkmark in the Internal column."