Comparisons
15 Email Uptime Monitoring Features To Look For In 2026
Discover the 15 essential email uptime monitoring features to look for in 2026 to prevent outages, improve email security, and ensure reliable email delivery.
Blog
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.
Browse by topic
Announcements (381) Email Security (303) Phishing Protection (151) DMARC (127) Email Services (77) Email Hosting (50) Data Privacy (38) Outbound SMTP (26)
Phishing Protection 7 min
Hackers Are Taking Over Microsoft 365 Accounts Without Stealing a Password
A new phishing wave takes over Microsoft 365 accounts without ever stealing a password, and it slips past MFA and standard URL scanning. Here is how the device code trick works and the layered defense that stops it.
Foundational
How GDPR Email Compliance Affects Marketing, Consent, And Data Privacy
Learn how GDPR email compliance impacts marketing, consent, and data privacy while improving transparency, trust, and lawful email communication practices.
News
Aflac Japan Breach, HSIN Cyberattack Confirmed, Foxconn Ransomware Claimed – Cybersecurity News [June 29, 2026]
Stay updated on this week's top cybersecurity news, including major data breaches, ransomware attacks, exploited flaws, AI threats, and email security risks.
Intermediate
12 Ways To Maintain Email Deliverability After Completing Email Warm-Up
Learn 12 proven ways to maintain email deliverability after completing email warm-up, improve inbox placement, protect sender reputation, and boost engagement.
Guides
How to Configure SPF for Get A Newsletter: A Complete Setup Guide
Configure SPF for Get A Newsletter with this step-by-step guide. Learn how to publish, verify, and optimize your SPF record for better email security.
Tutorials
How To Perform An Email Blacklist Check Before Sending Large Campaigns
Check your email domain and IP against major blacklists before large campaigns to improve deliverability, avoid spam filters, and protect sender reputation.
Intermediate
10 Email Retention Strategies For Managing High-Volume Mailboxes
Discover 10 email retention strategies for managing high-volume mailboxes, improving compliance, reducing storage costs, and strengthening email security.
Intermediate
We Are Open-Sourcing Commando.io: Server Automation Meets the LLM Era
DuoCircle is winding down the hosted Commando.io service and open-sourcing the code. Here is why we think pairing webhook-driven server recipes with an LLM is worth building in the open.
News
Tata Ransomware Leak, Bajaj Cyberattack Disrupts, Fortinet Firewalls Compromised – Cybersecurity News [June 22, 2026]
Weekly cybersecurity roundup: Tata & Bajaj ransomware, Fortinet credential breach, Linux kernel flaws, malware takedowns, global cyber threats and FIFA risks 2026
Foundational
5 Best AI Note Takers for Sales Calls in 2026
Discover the 5 best AI note takers for sales calls in 2026. Compare features, pricing, CRM integrations, and automation to boost sales productivity.
Advanced
How To Build An Email Infrastructure Monitoring Dashboard That Actually Prevents Outages
Build an email infrastructure monitoring dashboard that detects delivery issues, tracks SMTP health, and provides real-time alerts to prevent costly outages
Guides
How to Configure DKIM for Squarespace to Improve Email Security and Deliverability
Learn how to configure DKIM for Squarespace to improve email security, prevent spoofing, boost deliverability, and strengthen SPF and DMARC authentication.
Tutorials
How To Add A DKIM Record (V=DKIM1) In 5 Simple Steps
Learn how to add a DKIM record (v=DKIM1) in 5 simple steps. Improve email authentication, prevent spoofing, and boost email deliverability.
Advanced
DKIM Deployment For Multi-Tenant SAAS Platforms: Best Practices For Secure Email Authentication
Learn DKIM deployment best practices for multi-tenant SaaS platforms. Improve email security, prevent spoofing, and ensure trusted email authentication.
News
ShinyHunters Targets Kodak, Operation Endgame Success, One Medical Breach – Cybersecurity News [June 15, 2026]
Cybersecurity News June 2026: ShinyHunters targets Kodak and One Medical, Operation Endgame disrupts SocGholish, and critical flaws impact major platforms.
Comparisons
12 Best DMARC Reporting Solutions That Provide Actionable Email Authentication Insights
Discover the 12 best DMARC reporting solutions that deliver actionable email authentication insights, helping improve security, visibility, and compliance.
Tutorials
How to Configure SPF for Network Solutions (NetSol)
Learn how to configure SPF for Network Solutions, authorize sending servers, prevent email spoofing, and improve email deliverability with proper SPF setup.
Intermediate
How To Verify DMARC Records For Multiple Domains From A Single Dashboard
Verify DMARC records across multiple domains from a single dashboard, simplify monitoring, improve email security, and ensure policy compliance efficiently.
Intermediate
15 Email Migration Service Features That Matter Most for Growing Businesses
Discover 15 essential email migration service features that ensure secure data transfer, minimal downtime, compliance, scalability, and business growth.
News
Oracle Zero-Day Breach, VPN Security Alert, ServiceNow Denies Breach – Cybersecurity News [June 08, 2026]
Stay informed on the latest cyber threats, including Oracle zero-days, VPN exploits, ransomware attacks, data breaches, and phishing scams.
Advanced
Mail Server Authentication Strategies For High-Volume Email Senders
Learn effective Mail Server Authentication strategies for high-volume email senders to improve deliverability, prevent spoofing, and strengthen email security.
Guides
Pros and Cons of Tenant-to-Tenant Email Migrations in Regulated Industries
Explore the pros, cons, and compliance risks of Microsoft 365 tenant to tenant migrations. Learn how teams in regulated industries can protect data integrity.
Intermediate
How to Configure SPF, DKIM, and DMARC for Amazon SES
Learn how to configure SPF, DKIM, and DMARC for Amazon SES to improve email security, prevent spoofing, and boost email deliverability.
Guides
How to Strengthen Outbound SMTP for Fintech Firms to Safeguard Customer Emails
Struggling to protect customer emails? Discover how modern SMTP for fintech secures against phishing, enhances deliverability, and safeguards sensitive data.
Advanced
10 DKIM Key Rotation Checklist Mistakes That Break Email Deliverability
Avoid these 10 DKIM key rotation checklist mistakes that weaken email security, break authentication, and damage email deliverability rates.
Intermediate
SPF Include Mechanism Explained: Balancing Deliverability, Security, And Scalability
Learn how SPF include mechanisms improve email deliverability, strengthen email security, and support scalable SPF record management.
News
DentaQuest Data Leak, Cisco Patch Pending, Instagram Security Bug – Cybersecurity News [June 01, 2026]
Stay updated with the latest cybersecurity news: DentaQuest breach, Cisco zero-day, Instagram bug, supply chain attacks, and emerging cyber threats.
Intermediate
11 Preventing SPF Configuration Errors Recommendations For Managed Service Providers (MSPs)
Prevent SPF configuration errors with these 11 MSP recommendations to improve email authentication, boost deliverability, and strengthen domain security
Intermediate
SQL Injection Prevention: Essential Strategies for Securing Modern Applications
Protect your web applications from SQL injection attacks with proven prevention strategies, secure coding practices, input validation, and layered defenses.
Advanced
Office 365 Migration Solution: Security Risks To Avoid When Migrating Sensitive Business Data
Avoid costly security risks during an Office 365 migration solution. Protect sensitive business data with best practices for secure migration.
Intermediate
10 DKIM Authentication Testing Reports Every Security Team Should Review
Review 10 essential DKIM authentication testing reports that help security teams identify misconfigurations, improve deliverability, and stop spoofing.
News
FBI Warns Firms, Carnival Data Breach, GlobalProtect Exploits Active – Cybersecurity News [May 25, 2026]
Cybersecurity News: FBI warns of Silent Ransom attacks, Carnival confirms 6M-record breach, GlobalProtect exploits surge, and AI-powered threats grow.
Intermediate
DNS Vulnerabilities: Major Threats, Risks, and How to Reduce Exposure
Learn about major DNS vulnerabilities, security risks, and proven ways to reduce exposure, prevent attacks, and strengthen your domain protection.
Intermediate
How To Verify Sender Policy Framework Compliance Using SPF Lookup Tools
Verify Sender Policy Framework compliance using SPF lookup tools to identify record issues, improve email authentication, and enhance deliverability.
Intermediate
15 SPF Record Validation Mistakes That Cause Email Delivery Failures
Avoid these 15 SPF record validation mistakes that can trigger email delivery failures, authentication issues, spam filtering, and domain reputation damage.
News
GitHub Code Leak, 7-Eleven Breached, NYC Patient Exposure – Cybersecurity News [May 18, 2026]
Massive cyberattacks hit GitHub, 7-Eleven, NYC hospitals, and more. Explore the biggest cybersecurity threats and breaches from May 18, 2026.
Intermediate
Preventing Business Email Disruption Through An Invalid DKIM Selector Fix Process
Prevent business email disruption by fixing invalid DKIM selectors quickly to improve email authentication, deliverability, and domain trust.
Intermediate
20 Common Threats To Domain Reputation Protection And How To Avoid Them
Learn the top threats to domain reputation and how to avoid them to keep your email and online presence secure.
Intermediate
20 Common Threats To Domain Reputation Protection And How To Avoid Them
Learn the top threats to domain reputation and how to avoid them to keep your email and online presence secure.
Foundational
What Is GPS Spoofing? A Detailed Guide
Learn what GPS spoofing is, how it manipulates location data, the risks it creates, and the methods used to detect and prevent spoofing attacks.
Intermediate
Using Machine Learning For Malicious Email Detection And Phishing Defense
Machine learning helps detect malicious emails and phishing attacks faster, improving email security and reducing cyber threats.
Intermediate
7 Quick Fixes For SPF Authentication Failure In Microsoft 365 And Exchange Online
Fix SPF authentication failures in Microsoft 365 and Exchange Online with 7 quick solutions to improve email delivery, stop spoofing, and protect domains.
News
Cisco SD-WAN Flaw, Critical NGINX Exploit, Foxconn Ransomware Attack – Cybersecurity News [May 11, 2026]
Critical cybersecurity threats emerge as Cisco SD-WAN, NGINX, Microsoft Exchange, and PAN-OS flaws face active exploitation worldwide.
Foundational
11 Common Malware Types and How to Spot Them
Learn about 11 common malware types, how they spread, and the warning signs to help protect your devices and data online.
Email Services 8 min
5 Reasons To Test SPF Configuration Before Sending Emails
Testing your SPF configuration before a campaign goes live is a core part of modern email authentication.
Email Security 13 min
Your Vendors Are Your Weakest Link: How Third-Party Email Compromise Doubled in One Year and What SMBs Can Do About It
A data-driven analysis with 20+ primary-source statistics from Verizon, IBM, SecurityScorecard, the FBI, the World Economic Forum, and others.
Email Services 8 min
How To Validate A DMARC Record Generator Output Before Publishing DNS Changes
A DMARC record generator can simplify the process of creating a DMARC policy, but generating the record is only the first step.
Announcements 8 min
Zara Data Exposed, Medtronic Cyberattack Confirmed, Trellix Repository Breached – Cybersecurity News [May 04, 2026]
Here’s your weekly roundup of the most important cybersecurity stories from the past week, covering major data breaches, critical vulnerabilities.
Email Services 8 min
7 DKIM DNS Configuration Strategies For Hybrid Cloud Email Systems
Contemporary businesses seldom depend on a singular email setup.
Email Security 5 min
Email Monitoring Tools: A Complete Guide to Protecting Your Email Ecosystem
Email continues to be one of the most essential communication channels for businesses—but it’s also one of the most targeted by cyber threats.
Cybersecurity 19 min
The State of Cybersecurity in 2026: What the Data Tells Us, What It Means, and What to Do Next
A data-driven analysis of 26 primary-source statistics from institutional reports by the World Economic Forum, IBM, Verizon, Cisco, Accenture, ISC2, NIST.
Email Services 8 min
SPF Lookup Failure Troubleshooting: Why Your SPF Record Breaks And How To Fix It
Email authentication serves as the foundation for effective email deliverability.
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.
Email Services 7 min
11 SPF Validation Tool Checks You Should Run Before Sending Bulk Emails
Email marketing campaigns have the potential to enhance engagement, boost conversions.
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.
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