Segurança

Caixa de ferramentas Google: https://toolbox.googleapps.com/apps/checkmx/

SPF: Sender Policy Framework

https://support.google.com/a/answer/10684623

DKIM: DomainKeys Identified Mail

https://support.google.com/a/answer/180504

DMARC: Domain-based Message Authentication, Reporting, and Conformance

https://support.google.com/a/answer/2466563

Configure DomainKeys Identified Mail (DKIM) and Sender Policy Framework (SPF) before configuring DMARC. DKIM and SPF should be authenticating messages for at least 48 hours before turning on DMARC.

Exemplo string Dmarc:

v=DMARC1; p=reject; rua=mailto:postmaster@solarmora.com, mailto:dmarc@solarmora.com; pct=100; adkim=s; aspf=s

v=DMARC1; p=none; sp=none; pct=100; rua=mailto:noreply@cfmbm.info; ruf=mailto:noreply@cfmbm.info; ri=86400; aspf=s; adkim=s; fo=1