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Email Deliverability Deep Dive — SPF, DKIM, DMARC Print

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If your mail lands in spam, these three DNS records are the first thing to fix. All are TXT records — see the DNS article for how to add them.

SPF — who may send for your domain

v=spf1 a mx include:yourprovider.com ~all

  • List every legitimate sender: your mail host, your website/server (if it sends form mail), your campaign tool.
  • Only one SPF record allowed. Merge includes into a single record.
  • Stay under 10 DNS lookups or SPF breaks silently.

DKIM — cryptographic signature

  • Your mail provider generates a key pair; you publish the public key at selector._domainkey.yourdomain.com.
  • Receivers verify each message was really sent by you and not altered in transit.

DMARC — the policy that ties it together

_dmarc: v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com

  1. Start with p=none and read the reports for 2–4 weeks.
  2. Move to p=quarantine, then p=reject once all legit senders pass.

Testing

  • Send a test to a Gmail account → open "Show original" → confirm SPF/DKIM/DMARC all show PASS.
  • mail-tester.com gives a one-shot deliverability score with specific fixes.

Domains hosted with us get SPF and DKIM configured automatically; open a ticket for a free DMARC setup review.


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