Sender Policy Framework (SPF) is an extension to the Simple Mail Transfer Protocol (SMTP). SPF allows software to identify and reject forged addresses in the SMTP MAIL FROM (Return-Path), a typical nuisance in e-mail spam. SPF is defined in Experimental RFC 44 08.

Sender ID is an anti-spoofing proposal from the former MARID IETF working group that joined Sender Policy Framework (SPF) and Caller ID. Sender ID is defined primarily in Experimental RFC 4406, but additional parts in RFC 4405, RFC 4407 and RFC 4408.

The Sender ID proposal had become the subject of controversy regarding intellectual property licensing issues: Microsoft holds patents on key parts of Sender ID and used to license those patents under terms that were not compatible with the GNU General Public License and which were considered problematic for free software implementations in general. On October 23, 2006, Microsoft placed those patents under the Open Specification Promise, which is compatible with free and open source licenses.

What SPF record does Belgacom publish?

For Belgacom Secure Mail customers, the following record is available:

     v=spf1 ip4: ?all

Belgacom ISP domains publish the following record:

     v=spf1 include:ispmail.spf.secure-mail.be include:bgc.spf.secure-mail.be ip4: ~all