Email authentication guides

Fix an SPF error, configure your sending services, or work through an email authentication audit. Start with the problem you need to solve.

How to fix “SPF too many DNS lookups”

Fix SPF lookup-limit errors with a worked example, nested-include checks, safe cleanup steps and guidance on when SPF flattening helps.

5 min read

Multiple SPF records: how to combine them safely

Learn how to merge multiple SPF TXT records without losing legitimate senders, changing policy unintentionally or exceeding the DNS lookup limit.

5 min read

SPF flattening explained: manual vs automated management

Understand SPF flattening, compare manual and automated maintenance, and learn about changing provider IPs, policy limits and when flattening is unnecessary.

5 min read

Microsoft 365 SPF records: setup, examples and common errors

Set up SPF for Microsoft 365, handle additional sending services, avoid duplicate records and verify SPF, DKIM and DMARC on received messages.

5 min read

Google Workspace SPF setup when you use other email services

Configure Google Workspace SPF alongside newsletters, forms and other senders. Find the right DNS names, avoid duplicate records and test authentication.

5 min read

Why DMARC fails even when SPF passes

Diagnose SPF pass with DMARC fail using annotated message headers. Understand Return-Path, DKIM alignment, strict policies and the right fix for each case.

5 min read

Do subdomains need their own SPF records?

Learn when a subdomain needs SPF, why parent policies do not automatically apply, and how separate MAIL FROM domains affect lookup limits and DMARC alignment.

5 min read

An MSP’s SPF audit checklist for client domains

Audit client SPF records with a practical checklist covering sender inventory, DNS evidence, authentication tests, remediation ownership and ongoing reviews.

6 min read

What is SPF?

What an SPF record does, which domain it checks and how to read a simple example.

4 min read

SPF, DKIM and DMARC

What each check does and how they work together to authenticate your email.

3 min read

Changing email providers

What to check when adding a sending service, switching providers or removing an old one.

3 min read

Tools and checklists

Find services referenced in your SPF records, or keep track of a provider change.

Find your email servicesView checklist for changing providersDownload checklist (PDF)

Start your service list from a domain lookup, confirm what you use, and export it for Excel.