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Mastering Postmark SPF & DKIM Setup — An AutoSPF Guide to Bulletproof Email Authentication
ByBrad Slavin January 8, 2026January 8, 2026 Reading Time: 6 minutes

When you send email from your systems — whether it’s transactional notifications, marketing campaigns, or account alerts — the goal isn’t just delivery: it’s trust. Internet Service Providers (ISPs), mailbox providers, and modern spam filters are ruthlessly strict. Without the right authentication protocols in place, even legitimate mail can end up in the spam folder…

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Advanced

How can I fix an spf permerror caused by an overly long SPF record?
ByBrad Slavin January 7, 2026January 7, 2026 Reading Time: 11 minutes

To fix an SPF PermError caused by an overly long SPF record, you must diagnose the exact cause (string length, DNS lookup count, or syntax), then shorten and restructure the policy by removing obsolete senders, aggregating IPs, splitting or delegating via include/redirect, or safely flattening with monitoring—all validated before rollout and continuously monitored thereafter (AutoSPF…

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Intermediate

AutoSPF Explains: The Definitive Guide to Adding an SPF Record to Cloudflare
ByBrad Slavin January 7, 2026January 7, 2026 Reading Time: 6 minutes

Email is one of the most powerful communication tools in the digital age — but with that power comes responsibility. If you’re running a domain that sends emails — whether transactional messages, newsletters, or internal team emails — you must authenticate those messages correctly. Without proper authentication, your emails risk being tagged as spam, blocked,…

Read More AutoSPF Explains: The Definitive Guide to Adding an SPF Record to Cloudflare
Advanced

Mastering DKIM alignment: keys, signatures, and the real reasons emails fail verification
ByBrad Slavin January 6, 2026January 7, 2026 Reading Time: 6 minutes

When you send an email, it doesn’t reach the recipient directly; it has to go through a complex journey before it lands in the inbox. And along the way, it is prone to being tampered with by the attackers who are always on the lookout for opportunities to exploit weak or inconsistent authentication. To avoid…

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Foundational

How can I interpret the “pass”, “fail”, and “neutral” results from an SPF checker?
ByBrad Slavin January 6, 2026January 6, 2026 Reading Time: 12 minutes

An SPF “pass” means the connecting IP is authorized to send mail for the checked identity (MAIL FROM or HELO) per the domain’s SPF record, a “fail” means the IP is explicitly not authorized by the policy (often via -all or a negatively qualified match), and “neutral” means the domain made no assertion (e.g., ?all)…

Read More How can I interpret the “pass”, “fail”, and “neutral” results from an SPF checker?
Foundational

SPF Authentication Explained by AutoSPF: Why the ‘all’ Mechanism Matters and How To Use It Well
ByBrad Slavin January 6, 2026January 6, 2026 Reading Time: 6 minutes

Email authentication plays a foundational role in protecting your domain, your brand reputation, and your users from phishing, spoofing, and other malicious activity. Among the core authentication technologies — SPF, DKIM, and DMARC — SPF (Sender Policy Framework) is often one of the first layers of defense domain owners implement. However, even after publishing an…

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Foundational

What are the most common SPF record mechanisms and modifiers in the syntax?
ByBrad Slavin January 5, 2026January 5, 2026 Reading Time: 10 minutes

The most common SPF mechanisms are a, mx, ip4, ip6, include, exists, ptr (discouraged), and all, each optionally prefixed by qualifiers + (pass), – (fail), ~ (softfail), or ? (neutral), and the primary modifiers are redirect= and exp=, which respectively delegate evaluation to another domain’s SPF and provide a human-readable failure explanation. SPF (Sender Policy…

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Intermediate

Mastering SparkPost SPF & DKIM Setup — A Complete Guide by AutoSPF
ByBrad Slavin January 5, 2026January 5, 2026 Reading Time: 6 minutes

In today’s email ecosystem, ensuring that your messages actually reach the inbox — and aren’t mistaken for spam or phishing — is more critical than ever. This is where email authentication comes into play. Two primary pillars of email authentication are SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail). When paired with DMARC, they…

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Intermediate

SpamHero SPF & DKIM Configuration: The Complete Guide from AutoSPF
ByBrad Slavin January 3, 2026January 3, 2026 Reading Time: 7 minutes

At AutoSPF, we know that email authentication isn’t an optional add-on — it’s a foundational requirement for any business that wants reliable inbox delivery and protection from fraud, spoofing, and malicious impersonation. When you’re using an email security service like SpamHero, proper setup of Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) records is…

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Intermediate

Which IP addresses and domains should be included in an SPF record for Office 365?
ByBrad Slavin January 3, 2026January 3, 2026 Reading Time: 10 minutes

For Office 365 (Microsoft 365 Exchange Online), your SPF record should at minimum be v=spf1 include:spf.protection.outlook.com -all (or include:spf.protection.office365.us for US Government GCC High/DoD and include:spf.protection.partner.outlook.cn for 21Vianet China), plus ip4/ip6 entries for any on-premises/hybrid relays and include mechanisms or explicit IPs for any other authorized third-party senders. Sender Policy Framework (SPF) tells receiving servers…

Read More Which IP addresses and domains should be included in an SPF record for Office 365?