fast and secure postfix graylisting policy server
RFC 6647 graylisting policy server, following the recommended practice noted in the standard document. Graylisting defers message acceptance (for a specific recipient / sender / client_address value tuple) a configurable number of times via a standardized SMTP response (see allow(5), RFC 5321), which does not prevent message delivery from SMTP M(ail) T(ransfer) A(gent)s, but can help against simple spam producing programs. s-postgray clients are started via spawn(8), as shown in the manual. The server is started by clients as necessary, but it can be --startup also since v0.8.0. s-postgray needs to be configured as the builtin DB store path is /tmp (see manual), user and group settings are inherited from spawn(8) (or the environment which uses --startup).
Homepage: https://www.sdaoden.eu/code.html\#s-postgray
Maintainer: Steffen Nurpmeso <steffen@sdaoden.eu>