DMARC Tools
SPF
An SPF Record is used to indicate which email hosts is authorized to send mail on the specified domain's behalf. This query is used to get the authorized domains.
DKIM
DomainKeys Identified Message (DKIM) is one of the email authentication standards that underpins DMARC.
DMARC
A DMARC Record is used to authenticate email 'From:' addresses and defines policies on where to report both authorized and unauthorized mail flow.