opensmtpd-filter-spfgreylist

SPF-aware greylisting filter for the OpenSMTPD daemon

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  1. Package version
    opensmtpd-filter-spfgreylist-1.0.0
  2. Maintainer
    The OpenBSD ports mailing-list

This filter implements greylisting, allowing OpenSMTPD to temporarily
reject sessions of clients it has not seen before. Unlike many
implementations, this one is SPF-aware so it will properly handle
greylisting for domains doing relaying through multiple MX, as long as
they publish a valid SPF record.

The filter currently supports:

* IPv4 and IPv6 address greylisting
* SPF greylisting
* startup whitelisting of IP and domains
* automatically renewed whitelisting

+-----------------------------------------------------------------------
| Running ${PKGSTEM} on OpenBSD
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The filter itself requires no configuration.

It must be declared in smtpd.conf and attached to a listener for
sessions to go through greylisting:

filter "greylist" proc-exec "filter-spfgreylist"

listen on all filter "greylist"

It is possible to tweak the greylisting parameters, here listed with
default values in seconds:

* -passtime 300 accept greylisting retries only after 5 minutes from
initial attempt
* -greyexp 14400 expire greylisting attempts after 4 hours without a
retry
* -whiteexp 2592000 expire whitelisting after 30 days without any
attempt at delivery

It is also possible to inject IP and domains in the whitelists at
startup to avoid greylisting:

* -wl-ip <filename> inject IP addresses listed, one per line, in the
parameter file to the whitelist
* -wl-domain <filename> inject domains listed, one per line, in the
parameter file to the whitelist

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