Found a cool filter for Exchange that allows SPF filtering. This filter will become part of GFI mail essentials but at the moment is freeware!
It filters incoming mail and also tags the header.
Here's an eventlog picture:
(Oops - I lost it when I moved my blog - Sorry!)
Here's a header entry:
Received-SPF: none (chef.thefoleyhouse.ad: 188.8.131.52 is neither permitted nor denied by domain of listserve.novatech.co.uk) client-ip=184.108.40.206; firstname.lastname@example.org; helo=port-80.novatech.sc.newnet.co.uk;