Starting February 2024, Google and Yahoo require bulk senders to have DMARC, SPF and DKIM properly configured — emails failing these checks will be rejected or marked as spam.
Who is Affected
- Anyone sending more than 5,000 emails per day to Gmail/Yahoo
- All transactional email senders (newsletters, notifications)
- Any domain without proper authentication records
Required DNS Records
# SPF record — add to your domain DNS
yourdomain.com TXT "v=spf1 include:yourserver.com ~all"
# DKIM record — generate key and add to DNS
mail._domainkey.yourdomain.com TXT "v=DKIM1; k=rsa; p=YOUR_PUBLIC_KEY"
# DMARC record — minimum requirement
_dmarc.yourdomain.com TXT "v=DMARC1; p=none; rua=mailto:[email protected]"Verify Your Setup
# Check SPF
dig TXT yourdomain.com | grep spf
# Check DKIM
dig TXT mail._domainkey.yourdomain.com
# Check DMARC
dig TXT _dmarc.yourdomain.com
# Send test email and check headers
# Use: https://www.mail-tester.comConfigure Postfix DKIM
apt install opendkim opendkim-tools -y
opendkim-genkey -s mail -d yourdomain.com
# Add generated key to DNS
# Configure /etc/opendkim.confDMARC Policy Progression
# Start with monitoring (p=none)
"v=DMARC1; p=none; rua=mailto:[email protected]"
# Move to quarantine after reviewing reports
"v=DMARC1; p=quarantine; pct=50; rua=mailto:[email protected]"
# Full enforcement
"v=DMARC1; p=reject; rua=mailto:[email protected]"Conclusion
DMARC enforcement is now mandatory for reliable email delivery. Our team configures complete email authentication including SPF, DKIM and DMARC for all server environments.
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