DKIM SPF DMARC: Complete Email Authentication for PostMTA

DKIM, SPF & DMARC: Complete Email Authentication Setup for PostMTA

Email authentication is non-negotiable for deliverability. Here's how to configure it properly with PostMTA.

DNS Records You Need

SPF Record (TXT record for your sending domain):

v=spf1 include:_spf.postmta.com ~all

DKIM Record (TXT record — PostMTA generates the key):

postmta._domainkey IN TXT ( "v=DKIM1; k=rsa; p=YOUR_PUBLIC_KEY" )

DMARC Record (TXT at _dmarc.yourdomain.com):

v=DMARC1; p=quarantine; rua=mailto:[e-mail]; pct=100

PostMTA Authentication Features

• Automatic DKIM signing — Per-domain keys, rotated automatically
• SPF alignment — Strict alignment mode available
• DMARC reporting — Aggregate reports in dashboard
• Failover handling — Route around ISP blocks

Testing Your Setup

Use these tools to verify:

1. mail-tester.com — Full spam score analysis
2. mxtoolbox.com — DNS record checks
3. postmta.com/dashboard — Delivery analytics

Configure PostMTA authentication →