# How SPF, DKIM and DMARC Work

https://fiberserver.net.tr/knowledgebase/article/how-spf-dkim-dmarc-work

SPF, DKIM and DMARC are complementary email authentication mechanisms.

## SPF

SPF lists systems authorized to send for a domain. Maintain one valid SPF policy and include every legitimate sender.

## DKIM

DKIM adds a digital signature that recipients verify through a public DNS key.

## DMARC

DMARC evaluates alignment and tells recipients how to handle failures. Start with reporting, review legitimate sources and tighten policy gradually.

## Also check rDNS

Self-managed mail servers should use a consistent hostname, forward DNS and PTR record.