1.5 SPF, DKIM, and others

Sender Policy Framework, or SPF for short, is an extension to SMTP protocol that allows to identify forged identities supplied with the MAIL FROM and HELO commands. The framework is explained in detail in RFC 4408 (http://tools.ietf.org/html/rfc4408) and on the SPF Project Site.

Mailfromd provides a set of functions for using SPF to control mail flow. These are described in SPF Functions.

DomainKeys Identified Mail (DKIM) is an email authentication method designed to detect forged sender addresses in emails. Mailfromd supports both DKIM signing and verification. See DKIM, for a detailed description of these features.

Mailfromd also provides support for some third-party spam-abatement programs, namely SpamAssassin, and ClamAV. These are discussed in Interfaces to Third-Party Programs.