Skip to main content
ShieldMarc
Guides

DMARC, SPF, DKIM and email security guides

Step-by-step walkthroughs, explainers and troubleshooting for email authentication, DNS and domain security. Written for busy IT teams and UK MSPs.

Showing 21 of 47 resources

GuideApril 2026

Best DMARC Monitoring Tools 2026: A Comprehensive Comparison

Compare the best DMARC monitoring tools in 2026. Detailed feature comparison covering pricing, features, free tools, and who each platform is best for.

GuideApril 2026

How to Set Up DMARC for Google Workspace

Step-by-step guide to configuring DMARC, SPF, and DKIM for Google Workspace. Protect your domain from spoofing and improve Gmail deliverability.

GuideApril 2026

How to Set Up DMARC for Microsoft 365 (Office 365)

Step-by-step guide to configuring DMARC, SPF, and DKIM for Microsoft 365. Protect your organisation from email spoofing and improve deliverability.

GuideApril 2026

What is BIMI? Brand Indicators for Message Identification Explained

How BIMI displays your verified logo in Gmail, Apple Mail, and Yahoo, and what a VMC actually costs.

GuideApril 2026

DMARC p=quarantine vs p=reject: Which Policy Should You Use?

When to pick quarantine, when to pick reject, and how to move between them without breaking mail flow.

GuideApril 2026

DMARC for the NHS and UK Public Sector: A Post Mail Check Guide

How NHS trusts, councils, and gov.uk bodies can replace NCSC Mail Check with a UK owned, EU hosted platform.

GuideMarch 2026

What is DMARC? A Plain English Guide

DMARC explained for IT teams. What it does, how it works, and why you need it.

GuideMarch 2026

SPF vs DKIM vs DMARC: What's the Difference?

How SPF, DKIM, and DMARC work together to protect your domain from spoofing.

GuideMarch 2026

Understanding DMARC Reports: RUA and RUF Explained

How to read and act on DMARC aggregate and forensic reports.

GuideMarch 2026

SPF Hard Fail vs Soft Fail: Why ~all Is Safer with DMARC

When to use -all vs ~all in your SPF record and how DMARC changes the equation.

GuideMarch 2026

How to Fix SPF Too Many DNS Lookups

Diagnose and fix the 10 DNS lookup limit in SPF records.

GuideMarch 2026

NCSC Mail Check Has Retired: What UK Organisations Should Do Now

What the NCSC Mail Check retirement means and how to replace it.

GuideMarch 2026

SSL Certificate Monitoring: What to Check and When

Avoid certificate expiry incidents with proactive SSL monitoring.

GuideMarch 2026

What is MTA-STS and TLS-RPT? Securing Email in Transit

How MTA-STS enforces TLS for inbound email and TLS-RPT captures delivery failures.

GuideMarch 2026

What is DNSSEC? How DNS Signing Protects Your Domain

How DNSSEC prevents DNS spoofing and cache poisoning attacks.

GuideMarch 2026

CAA Records Explained: Control Who Issues Your SSL Certificates

Use CAA records to restrict which certificate authorities can issue certs for your domain.

GuideMarch 2026

DNS Record Types Explained: A, AAAA, MX, TXT, CNAME and More

A guide to every common DNS record type and what it does.

GuideMarch 2026

Domain Expiry and WHOIS: How to Protect Your Registration

Prevent domain hijacking and accidental lapses with registration monitoring.

GuideMarch 2026

Protecting Your Brand from Lookalike Domains

Detect and defend against typosquatting and brand impersonation domains.

GuideMarch 2026

How to Create SPF, DKIM, and DMARC Records: Step-by-Step

A step-by-step walkthrough for setting up email authentication from scratch.

GuideMarch 2026

How to Set Up DKIM: Step-by-Step for Every Email Provider

Provider-specific DKIM setup guides for Google Workspace, Microsoft 365, SendGrid, Mailchimp, and more.