Understand SPF, DKIM, DMARC and why email still reaches spam
Learn what each authentication result proves, how different sending systems use your domain and which evidence helps explain spam placement, blocking or missing mail.
Understand what SPF, DKIM and DMARC each prove
Authentication results identify infrastructure and domains. DMARC adds alignment with the visible From address.
Understand SPF and DKIMSee the different identity each method authenticates and where common configuration mistakes occur.Understand DMARC policies and reportsLearn how DMARC uses SPF or DKIM alignment, then reports what receivers observed.See why alignment changes the resultCompare the visible From domain with the SPF and DKIM identities.Set up DMARC without blocking legitimate sendersBegin with sender discovery and evidence before moving towards enforcement.
Understand why authenticated email can still reach spam
Authentication supports identity. Reputation, complaints, content, recipient response and sending patterns still affect placement.
Diagnose email deliverability problemsSeparate delivery from inbox placement and narrow the cause by route and provider.Investigate a sudden delivery changeRecord the symptom, recent changes, affected routes and evidence before making a correction.Use inbox-placement tests carefullyPlan representative tests and understand why seed results are samples rather than guarantees.Read the message headersFind route, authentication and provider-handling evidence in the original message.
Put sender reputation and blocklist warnings in context
A domain, IP address or shared service can carry different signals. Check whether real delivery changed.
Investigate an email blocklist alertIdentify the listed asset, provider relevance, underlying cause and recovery evidence.Use free reputation and provider checksCheck useful signals without treating a single score as a universal verdict.Decide whether warm-up fits the situationUnderstand the narrow use cases and what warm-up cannot repair.
Check current Gmail, Yahoo and Microsoft sender requirements
Provider rules change. Use dated guidance and original provider sources before changing production systems.
Review current provider requirementsSeparate requirements for all senders from additional duties that apply to bulk senders.Interpret Gmail 550 5.7.26Use the exact rejection text to check authentication and alignment.Understand one-click unsubscribeSee when RFC 8058 support matters and what it does not replace.Move DMARC towards enforcement safelyUse report evidence and sender ownership before changing policy.
More practical guides
Open the guide that matches the question or fault you are dealing with now.
DMARC record examples decoded: understand each tag before you copy anythingSee real DMARC TXT record examples and what each tag means: p=none, p=quarantine, p=reject, rua, aspf, adkim and sp=:Authenticate email sent by your website or applicationTrace form, shop and booking email through its real transport, configure the SPF or DKIM identity receivers actually check and stop website mail landing in spam.How to protect a parked or non-sending domain from email spoofingProtect a parked or non-sending domain from email spoofing. Publish restrictive SPF, DMARC and null MX records safely with rollback guidance.PECR and UK GDPR for business email: the two rules every sender must answerSeparate PECR channel rules from UK GDPR data duties so business email has a defensible sending route, without mixing consent, soft opt-in or lawful basis.