EMAIL AUTHENTICATION
SPF Basics: Defining Authorized Senders
Learn what SPF is, how it defines which servers may send email for your domain, how to read SPF records, and how to avoid common SPF mistakes.
Email Authentication Guides
Learn how SPF, DKIM, DMARC, MX records and reverse DNS affect email authentication, trust and deliverability.
Topics covered:
SPFDKIMDMARCMX records
21 articles
All Email Authentication guides
21 guides covering email authentication topics.
EMAIL AUTHENTICATION
Creating a Valid SPF Record: Common Syntax Mistakes
Learn how to create a valid SPF record, avoid duplicate SPF records, fix syntax mistakes, and stay within SPF DNS lookup limits.
EMAIL AUTHENTICATION
SPF Qualifiers and Mechanisms Explained
Learn what SPF mechanisms and qualifiers mean, how include, ip4, ip6, a, mx, redirect and all work, and how to avoid risky SPF configurations.
EMAIL AUTHENTICATION
Understanding SPF's 10 DNS Lookup Limit
Learn what SPF’s 10 DNS lookup limit means, which mechanisms count toward it, why SPF permerror happens, and how to reduce lookup count safely.
EMAIL AUTHENTICATION
Why You Should Avoid +all in Your SPF Record
Learn what +all means in SPF, why it weakens email authentication, and how to replace it with a safer SPF policy.
EMAIL AUTHENTICATION
SPF When Using Multiple Email Providers
Learn how to configure one SPF record for multiple sending services, avoid duplicate SPF records, and stay within SPF’s DNS lookup limit.
EMAIL AUTHENTICATION
DKIM Signatures: How They Work and Why They Matter
Learn what DKIM is, how DKIM signatures verify email, what selectors and public keys do, and how to fix common DKIM configuration problems.
EMAIL AUTHENTICATION
Choosing a DKIM Selector and Publishing the Public Key
Learn what a DKIM selector is, where to publish the DKIM public key, how to avoid common DNS mistakes, and how to rotate DKIM keys safely.
EMAIL AUTHENTICATION
DMARC for Beginners: Policies, Alignment and Enforcement
Learn what DMARC is, how SPF and DKIM alignment work, what p=none, quarantine and reject mean, and how to enforce DMARC safely.
EMAIL AUTHENTICATION
Understanding DMARC Alignment
Learn what DMARC alignment means, how SPF and DKIM alignment work, and why SPF or DKIM can pass while DMARC still fails.
EMAIL AUTHENTICATION
How to Read DMARC Aggregate and Forensic Reports
Learn what DMARC aggregate and forensic reports are, what data they contain, and how to use them before moving to quarantine or reject.
EMAIL AUTHENTICATION
Moving from p=none to p=quarantine or reject
Learn when and how to move DMARC from monitoring to enforcement, review reports, fix legitimate senders and avoid blocking real mail.
EMAIL AUTHENTICATION
Configuring rua and ruf Tags in DMARC
Learn what rua and ruf mean in DMARC, how to configure aggregate and forensic reporting addresses, and when to use each tag safely.
EMAIL AUTHENTICATION
DMARC Subdomain Policies: Using the sp= Tag
Learn how DMARC applies to subdomains, what the sp= tag does, when subdomains inherit policy, and how to avoid blocking legitimate subdomain mail.
EMAIL AUTHENTICATION
Best Practices for MX Records and Mail Routing
Learn how MX records route incoming email, how MX priority works, and how to avoid common mail routing mistakes during setup or migration.
EMAIL AUTHENTICATION
Google Workspace Email Authentication: SPF, DKIM and DMARC
Learn how to configure Google Workspace email authentication with MX records, SPF, DKIM and DMARC, and avoid common DNS mistakes.
EMAIL AUTHENTICATION
Microsoft 365 Email DNS Setup: SPF, DKIM and DMARC
Learn how to configure Microsoft 365 email DNS with MX records, SPF, DKIM and DMARC, and avoid common migration and authentication mistakes.
EMAIL AUTHENTICATION
Why Reverse DNS Matters for Email Deliverability
Learn what reverse DNS is, why PTR records matter for mail servers, how forward-confirmed reverse DNS works, and how to fix common rDNS problems.
EMAIL AUTHENTICATION
Email Authentication for Transactional Email Services
Learn how to authenticate transactional email services with SPF, DKIM, custom Return-Path and DMARC alignment.
EMAIL AUTHENTICATION
BIMI Explained: Adding Logos to Your Emails
Learn what BIMI is, how it connects brand logos to authenticated email, what DNS records are required, and why DMARC enforcement matters.
EMAIL AUTHENTICATION
What Is ARC and Do You Need It
Learn what ARC is, how it helps preserve email authentication results during forwarding, and when domain owners, mail providers or gateways may need it.
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