This module is intended to delay messages that have spam score above
greylisting action threshold.
Greylisting module saves 2 hashes for each message in Redis:
IP address is stored with certain mask applied: it is
/19 for IPv4 and
/64 for IPv6 accordingly. Each hash has its own timestamp and Rspamd checks for the following times:
greylistingtime - when a message should be temporary rejected
expiretime - when a greylisting hash is stored in Redis
The hashes lifetime is depicted in the following scheme:
This module produces
soft reject action on greylisting which SHOULD be treated as temporary rejection by MTA (usually via Milter interface). Exim can recognise it with configuration - refer to the integration guide for details. Haraka supports it from v2.9.0.
First of all, you need to setup Redis server for storing hashes. This procedure is described in detail in the following document. Thereafter, you can modify a couple of options specific for greylisting module. It is recommended to define these options in
expire: setup hashes expire time (1 day by default)
greylist_min_score: messages with scores below this threshold are not greylisted (default unset)
ipv4_mask: mask to apply for IPv4 addresses (19 by default)
ipv6_mask: mask to apply for IPv6 addresses (64 by default)
key_prefix: prefix for hashes to store in Redis (
max_data_len: maximum length of data to be used for body hash (10kB by default)
message: a message for temporary rejection reason (
Try again laterby default)
timeout: defines greylisting timeout (5 min by default)
whitelisted_ip: map of IP addresses and/or subnets to skip greylisting for
whitelist_domains_url: map of hostnames and/or eSLDs of hostnames to skip greylisting for
report_time: tell when greylisting is epired (appended to
whitelist_symbols: skip greylisting when specific symbols have been found (from 1.9.1)
If you need to skip greylisting based on other conditions disabling the
GREYLIST_SAVE symbols with settings module might suffice.
To enable the module with default settings you need to define at least redis servers to store greylisting data:
# local.d/greylist.conf servers = "127.0.0.1:6379";
Adding servers to store greylisting data enables greylisting in Rspamd.