Australian Department of Defense Recommends SPF
SPF Part of the Recommended Information Security Practices
In their new version of the Australian Government Information Security Manual, the Defence Signals Directorate has recommended use of SPF in conjunction with other email related security technologies such as TLS and DKIM.
"6.6.177. Agencies should implement the email Sender Policy Framework (SPF) following the recommendations in IETF’s RFC 4408."