https://dmarc.org/resources/deployment-tools/
DKIM
https://dmarcian.com/dkim-validator/
https://dkimcore.org/c/keycheck
https://checkcybersecurity.service.ncsc.gov.uk/email-security-check/results?domain=icgconsultant.com
https://toolbox.googleapps.com/apps/checkmx/check?domain=icgconsultant.com&dkim_selector=
How to Turn On End-to-End Encryption in Gmail | Set up MTA-STS using your Google Admin Console