DKIM
https://support.google.com/a/answer/180504
Generate DKIM
https://powerdmarc.com/fr/dkim-record-generator/
DMARC
https://support.google.com/a/answer/2466563?sjid=732990820227783821-EU
https://support.google.com/a/answer/10032169?sjid=732990820227783821-EU
SPF
https://support.google.com/a/answer/10684623?hl=fr