Startups

Email authentication for startups: the 2026 checklist

If you are a startup sending email, you need to get into the inbox. Here is the complete 2026 checklist for email authentication.

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The free InboxProof audit checks SPF, DKIM, DMARC, MX, TLS, PTR, and IP reputation for your domain. No signup.

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1. SPF

SPF tells the world which servers are allowed to send email for your domain. Without it, your email will be rejected by most providers.

Run the free SPF checker to verify your SPF record is configured correctly.

2. DKIM

DKIM adds a digital signature to your email, proving it was sent by you and not tampered with. Without it, your email will fail authentication.

Run the free DKIM checker to verify your DKIM record is configured correctly.

3. DMARC

DMARC tells receiving servers what to do with email that fails SPF or DKIM. Without it, your domain is vulnerable to spoofing.

Run the free DMARC checker to verify your DMARC record is configured correctly.

4. MX

MX records tell the world which servers receive email for your domain. Without them, email to your domain will bounce.

The free audit checks your MX records and tells you if they are configured correctly.

5. TLS

TLS encrypts email in transit. Without it, your email is vulnerable to interception.

The free audit checks your TLS configuration and tells you if it is secure.

6. PTR

PTR records map your IP address back to a hostname. Without them, your email will be flagged as suspicious.

The free audit checks your PTR record and tells you if it is configured correctly.

7. IP reputation

Your IP address has a reputation. If it is on a blocklist, your email will be rejected.

The free audit checks your IP reputation and tells you if it is on any blocklists.

Run the full checklist

The free audit checks all seven records and shows the exact record to add.

Run the free audit

Want this checked automatically every day? Inboxproof Pro monitors your domain around the clock and alerts you the moment a record breaks or an IP gets listed. See pricing →

Related: SPF vs DKIM vs DMARC · How to set up a DMARC record · SPF, DKIM, DMARC for Google Workspace · SPF, DKIM, DMARC for Microsoft 365