Email Authentication

SPF, DKIM & DMARC: Build an Authenticated Sending Foundation

Understand the three core domain-authentication technologies used to help receiving systems evaluate legitimate email.

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Built for This Email Workflow

Use SMTP infrastructure, authentication and monitoring appropriate to your sending requirements.

SPF

SPF lets a domain publish which sending systems are authorized to send mail on its behalf.

DKIM

DKIM adds a cryptographic signature that receiving systems can validate against a public key published in DNS.

DMARC

DMARC builds on SPF and DKIM and lets domain owners publish policy and reporting instructions.

Domain Alignment

DMARC evaluation considers alignment between the visible From domain and authenticated identifiers.

DNS Configuration

Authentication depends on correctly publishing the required DNS records for your sending setup.

Deliverability Foundation

Authentication is important, but reputation, recipient consent, list quality, content and engagement also affect outcomes.

Common Use Cases

Start With Your Domain

Identify the domain you will use in the visible From address.

Publish Authentication Records

Configure the SPF, DKIM and DMARC records required for your sending environment.

Verify & Monitor

Confirm records are valid and monitor your sending behavior and reputation over time.

Deliverability matters: SMTP infrastructure can support a strong sending program, but inbox placement cannot be guaranteed. Authentication, sender reputation, recipient consent, list quality, content, engagement and receiving-provider decisions also affect delivery.

Frequently Asked Questions

Does SPF alone guarantee delivery?

No. SPF is one authentication signal and does not guarantee inbox placement.

Do I need DKIM and DMARC too?

Modern sending programs commonly use SPF, DKIM and DMARC together because they address different parts of domain authentication and policy.

Does SMTP-Plans support authentication setup?

The current SMTP-Plans pricing page describes SPF, DKIM and DMARC setup assistance.

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