# DKIM module

This module checks DKIM signatures for emails scanned. DKIM signatures can establish that this specific message has been signed by a trusted relay. For example, if a message comes from gmail.com then a valid DKIM signature means that this message was definitely signed by gmail.com (unless gmail.com private key has been compromised, which is not a likewise case).

## Supported features

Rspamd can deal with many types of DKIM signatures and messages canonicalisation. The major difficulty with DKIM are line endings: many MTA treat them differently which leads to broken signatures. Basically, rspamd treats all line endings as CR+LF that is compatible with the most of DKIM implementations. From the version 1.3, Rspamd DKIM module also supports signing of messages.

## Configuration

DKIM module has several useful configuration options:

• dkim_cache_size (or expire) - maximum size of DKIM keys cache
• whitelist - a map of domains that should not be checked with DKIM (e.g. if that domains have totally broken DKIM signer)
• domains - a map of domains that should have more strict scores for DKIM violation
• strict_multiplier - multiply the value of symbols by this value if received from domains map
• trusted_only - do not check DKIM signatures for all domains but those which are from the domains map

## DKIM signatures

Please use dkim_signing module for DKIM signatures. This module should not be used for these purposes any longer.