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Email security, in plain English.

Practical guidance on SPF, DKIM, DMARC, BIMI, phishing protection, and the parts of email infrastructure that quietly break things. Written by the DuoCircle team for people who run email and want to stop getting paged.

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Announcements (380) Email Security (301) Phishing Protection (150) DMARC (127) Email Services (72) Email Hosting (50) Data Privacy (38) Outbound SMTP (26)
Email Security 8 min

BIMI in 2026: What the Certificate Authority Does, and What Your DMARC Tool Does

BIMI confuses buyers because two different vendors handle two different jobs. Here is the clean split between VMC procurement (a Certificate Authority function) and BIMI hosting (what your DMARC reporting tool actually does).

SPF Records 7 min

When SPF Lookup Limits Actually Break Things: The 10-Lookup Rule, Permerror, and How to Stay Under It

The SPF 10-DNS-lookup limit silently breaks email authentication once you exceed it. Here is how to diagnose a permerror, why even careful organizations end up over the limit, and the fix options that actually work.

Outbound SMTP 7 min

Office Copiers Can't Authenticate to Microsoft 365 Anymore: Why It Broke and How to Fix It

Your scan-to-email died after a Microsoft 365 update. Here's why basic auth and SMTP AUTH got disabled, the three options your IT team actually has, and the fastest reliable fix.

DMARC 7 min

DMARC at p=none Is a Setup State, Not a Deployment

Publishing a DMARC record at p=none is the starting line, not the finish line. Here is what p=none actually does, what it does not, and how to move to enforcement without breaking legitimate mail.

Announcements 12 min

Medtronic Cyberattack Confirmed, cPanel Ransomware Wave, Root Access Granted – Cybersecurity News [April 27, 2026]

Here’s your weekly roundup of the most significant cybersecurity stories from the past week, covering major data breaches, critical vulnerabilities.

Email Services 6 min

How Poor Email Testing Is Silently Costing SaaS Companies Thousands

Email is one of the most critical communication channels for SaaS companies.

Email Security 12 min

Shadow AI in the Inbox: How Employees Using Unauthorized AI Tools Are Creating a New Email Security Crisis

A data-driven analysis with 20+ statistics from Verizon, IBM, Cisco, KPMG, LayerX, Microsoft, the World Economic Forum, and others.

SPF Records 8 min

How SPF Record all Affects Email Routing Across Hybrid Cloud Environments

In today’s digital landscape, especially within hybrid cloud frameworks, email authentication has become increasingly vital.

DMARC 5 min

Why DIY-ing DMARC could cost you more than you think

Why DIY-ing DMARC could cost you more than you think.

Email Services 7 min

7 Critical Factors to Consider Before You Buy SMTP Relay Services

Email remains an essential communication tool for businesses, utilized for everything from transactional notifications to marketing initiatives and customer.

Email Security 12 min

DMARC, SPF, and DKIM in 2026: Why Email Authentication Is Now a Regulatory Requirement, Not Just a Best Practice

A data-driven analysis with 20+ statistics from EasyDMARC, Google, Microsoft, IBM, Verizon, CISA, and the PCI Security Standards Council.

Email Security 8 min

Designing A Custom Dkim Architecture For High-Volume Email Senders

Organizations that send large volumes of emails, including software-as-a-service (SaaS) platforms, marketing automation providers.

Phishing Protection 11 min

AI-Generated Phishing Has Eliminated the Typo: Why Traditional Email Filters Are No Longer Enough

A data-driven analysis for security leaders, IT teams, and MSPs — with 20+ primary-source statistics from Microsoft, IBM, FBI IC3, KnowBe4, Verizon, Cisco.

Announcements 5 min

Sri Lanka Cyberattack, SilentGlass Threat Defense, Rituals Data Breach – Cybersecurity News [April 20, 2026]

Sri Lanka Cyberattack, SilentGlass Threat Defense, Rituals Data Breach – Cybersecurity News [April 20.

Email Services 8 min

How To Migrate From Windows SMTP Server To Cloud-Based SMTP Without Downtime

Transitioning from a Windows-based SMTP server to a cloud-hosted solution has evolved beyond simple modernization; it’s now a key strategic initiative aimed at.

Email Services 17 min

Trust by Design: Rethinking DKIM Settings for Modern Email

Email trust is no longer a background technical detail—it’s the foundation of how brands communicate, protect users.

Email Services 16 min

5 Best DKIM Record Examples To Understand Selectors, Key Lengths, And TXT Formatting

Why these DKIM record examples matter A well-formed DKIM record is the foundation of email authentication.

Announcements 5 min

UK Cyber Surge, Poland Incident Surge, Japan Shipping Attack – Cybersecurity News [April 13, 2026]

UK Cyber Surge, Poland Incident Surge, Japan Shipping Attack – Cybersecurity News [April 13.

Email Security 5 min

Enterprise email security: Here’s what you should know about it

When your organization operates at scale, emails don’t go out from one domain; they are sent from marketing platforms, HR systems, finance tools.

Email Security 18 min

Behind the Signature: A Curious Journey into DKIM Implementation

Every verified email has an unseen signature that plays a crucial role in establishing trust.

Email Security 9 min

9 Reliable Providers for a Managed outgoing SMTP email server Solution

In the fast-moving digital world of today, effective email delivery is essential for businesses that rely on smooth communication and customer interactions.

Email Security 9 min

The Signature Checkpoint: DKIM Testing at the Gates of the Inbox

As email security continues to advance, the inbox serves as a crucial entry point, with DKIM testing playing an essential role in its protection.

Announcements 5 min

Apple Pay Scam, Crypto Fraud Victims, Retirement Phishing Loss – Cybersecurity News [April 06, 2026]

Apple Pay Scam, Crypto Fraud Victims, Retirement Phishing Loss – Cybersecurity News [April 06.

DMARC 9 min

How ARC resolves email authentication for forwarded messages

How ARC resolves email authentication for forwarded messages.

Email Security 9 min

Avoiding Burn: How An SPF Generator For Godaddy Can Still Toast Your DMARC If Misused

The Sender Policy Framework is deceptively simple: publish a single SPF record as a TXT record in your domain DNS so receiving systems can check whether a.

Email Security 15 min

12 Best Hosted SMTP Servers for High Deliverability in 2026

Selecting the appropriate hosted SMTP server in 2026 is crucial for getting your emails delivered to the inbox rather than the spam folder.

Email Hosting 14 min

Inbox Wars: Winning with Powerful SMTP Email Hosting

In the bustling digital environment of today, the quest for consumer attention often starts with the inbox.

Announcements 5 min

LinkedIn Fraud Spike, SIM Scam Bust, UK VIPs Targeted – Cybersecurity News [March 30, 2026]

LinkedIn Fraud Spike, SIM Scam Bust, UK VIPs Targeted – Cybersecurity News [March 30.

Email Services 9 min

8 Genius Tricks to Master Your DKIM Validator Like a Pro

Navigating email authentication can often feel overwhelming, particularly when it comes to DKIM validation and ensuring your emails reach their intended.

Email Security 6 min

What happens when your DKIM key is compromised? How can you identify and fix the problem?

What happens when your DKIM key is compromised? How can you identify and fix the problem?

Phishing Protection 6 min

How Domain Verification Helps Prevent Email Phishing Attacks

Email is still the most exploited initial vector of attacks in cybersecurity.

Email Services 15 min

Set Up A DKIM Key For Microsoft 365 Custom Domains: A Step-By-Step Guide

This step-by-step guide explains how to prepare your Microsoft 365 tenant and custom domain to publish a DKIM record.

Email Security 15 min

How The Best Anti-Phishing Software Prevents Email-Based Attacks

Email-centric threats continue to be a prevalent and expensive cybersecurity challenge for both companies and individuals.

Announcements 5 min

AI Phishing Campaign, TikTok Phishing Targeted, Dutch Police Cyberattack – Cybersecurity News [March 23, 2026]

AI Phishing Campaign, TikTok Phishing Targeted, Dutch Police Cyberattack – Cybersecurity News [March 23.

DMARC 5 min

Why is DMARC important for the retail sector?

Why is DMARC important for the retail sector?

Announcements 5 min

Horabot Resurfaces Mexico, Aura Breach Compromise, Tax Season Threats – Cybersecurity News [March 16, 2026]

Horabot Resurfaces Mexico, Aura Breach Compromise, Tax Season Threats – Cybersecurity News [March 16.

Email Security 7 min

VMC vs CMC explained: Which logo certificate should you choose?

VMC vs CMC explained: Which logo certificate should you choose?

Announcements 4 min

Cambodia Targets Cybercriminals, Traditional Security Insufficient, AI Against Phishing – Cybersecurity News [March 09, 2026]

Cambodia Targets Cybercriminals, Traditional Security Insufficient, AI Against Phishing – Cybersecurity News [March 09.

Email Security 8 min

8 Best Tools To Test DKIM Records And Fix Signature Errors

Email authentication is vital for safeguarding your domain against spoofing and enhancing email deliverability.

Email Services 16 min

Troubleshoot Failed Signatures Using A DNS DKIM Lookup And Record Inspector

Email authentication plays a critical role in protecting your domain from spoofing and ensuring that your messages reach recipients’ inboxes.

Email Hosting 18 min

10 Steps To Set Up A Self-Hosted Mail Server Without Hitting Spam

Self-hosted email gives you control, privacy, and the flexibility to run open source software instead of relying entirely on a mail service provider.

Cybersecurity 5 min

NCSC announces the retirement of Mail Check and Web Check: Here’s what it really means

NCSC announces the retirement of Mail Check and Web Check: Here’s what it really means.

Announcements 6 min

LastPass Users Phished, Amazon Down US, UK Cybersecurity Boost – Cybersecurity News [March 02, 2026]

LastPass Users Phished, Amazon Down US, UK Cybersecurity Boost – Cybersecurity News [March 02.

DMARC 8 min

What is DMARC quarantine? Understanding the p=quarantine policy in 2026

Email authentication has moved far beyond a technical checkbox. In 2026, mailbox providers expect domains to actively enforce authentication policies to pr.

Email Security 16 min

Mail Relay Server Security: Preventing Spam And Unauthorized Access

What mail relay servers are, why they’re targeted, and the risks of misconfiguration A mail relay server is the SMTP-facing component that accepts, routes.

Data Privacy 5 min

Cutting Block Rates With Measurable Scraping Habits: Data, Proxies, and Proof

Most scraping failures are predictable once you measure the right things.

DMARC 16 min

8 Warning Signs Your Domain Needs A Dmarc Test Now

Improperly authenticated emails can leave your domain susceptible to issues such as spoofing, phishing, and undelivered messages, often without your awareness.

Email Security 7 min

From SMTP to Security: The Operational Layers Behind Reliable Email Delivery

Understanding the Email Delivery Ecosystem Email remains an essential communication channel for businesses worldwide, playing a critical role in marketing.

Data Privacy 8 min

Replacing Legacy CMS Platforms: When Webflow Makes Business Sense

Your website is the place prospects decide whether you feel credible, customers decide whether you feel current.

Email Security 16 min

Adding A DKIM Record In DNS For Better Email Security

Email security threats continue to evolve, making strong authentication more important than ever.

Announcements 5 min

UFP Cyber Compromise, Marseille Ticket Breach, Google Phishing Campaign – Cybersecurity News [February 23, 2026]

UFP Cyber Compromise, Marseille Ticket Breach, Google Phishing Campaign – Cybersecurity News [February 23.

DMARC 6 min

Deploying DMARC the right way: Here’s what MSPs and enterprises should know

Deploying DMARC the right way: Here’s what MSPs and enterprises should know.

DMARC 15 min

10 Ways To Master DMARC Failure Troubleshooting And Fix Email Authentication Fast

When a DMARC failure hits production, act methodically.

Email Security 14 min

Reducing Business Email Compromise with Microsoft 365 Zero Trust Email Security

Business email compromise remains one of the most costly advanced threats because it exploits trust, targets finance workflows.

DMARC 15 min

The DMARC Spoofing Visibility Report Explained: Detect And Block Email Spoofing And Phishing

Email spoofing and phishing attacks continue to target businesses of all sizes, making domain protection more critical than ever.

Announcements 5 min

Amazon AI Cyberattack, Odido Data Breach, German Rail Targeted – Cybersecurity News [February 16, 2026]

Amazon AI Cyberattack, Odido Data Breach, German Rail Targeted – Cybersecurity News [February 16.

DMARC 7 min

DMARC is now mandatory for Cyber Essentials Mark Certification from CSA

DMARC is now mandatory for Cyber Essentials Mark Certification from CSA.

Email Services 15 min

SMTP Deliverability Monitoring Explained: How It Works And Why It Matters

SMTP deliverability monitoring acts as an essential support system that assesses where your emails end up whether in the inbox, spam folder.

SPF Records 8 min

9 Proven Fixes For SPF Multiple Records Error In Email Authentication

Email authentication is critical to protecting your domain from spoofing, phishing.

DMARC 14 min

The ultimate DMARC Audit For Businesses Guide For MSPs And Service Providers: Reporting And Alignment

Email remains the primary attack vector for phishing and business email compromise, making DMARC a critical layer of protection for modern organizations.

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