# DuoCircle > DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. > We deliver about 90% of category-leader capability at roughly half the price, backed by experts who own the outcome. > Trusted by 50,000+ organizations since 2014. ## Authenticate - [SPF Management](https://www.duocircle.com/email/spf-management/) - [DMARC Reporting](https://www.duocircle.com/email/dmarc/) - [Mail Flow Monitoring](https://www.duocircle.com/email/mail-flow-monitoring/) - [All Authentication Products](https://www.duocircle.com/products/authenticate/) ## Protect - [Phishing Protection](https://www.duocircle.com/email/phishing-protection/) - [Spam Filtering](https://www.duocircle.com/email/spam-filtering/) - [Lotus Notes Email Security](https://www.duocircle.com/email/lotus-notes-email-security/) - [All Protection Products](https://www.duocircle.com/products/protect/) ## Deliver - [Outbound SMTP](https://www.duocircle.com/email/outbound-smtp/) - [Developer Email API](https://www.duocircle.com/email/developer-email-api/) - [Inbox Placement Testing](https://www.duocircle.com/email/inbox-placement-testing/) - [Cold Email Outreach](https://www.duocircle.com/email/cold-email-outreach/) - [All Delivery Products](https://www.duocircle.com/products/deliver/) ## Route - [Alumni Forwarding](https://www.duocircle.com/email/alumni-forwarding/) - [Tenant Migration](https://www.duocircle.com/email/tenant-migration/) - [Email Forwarding](https://www.duocircle.com/email/email-forwarding/) - [Backup MX](https://www.duocircle.com/email/email-backup-mx/) - [All Routing Products](https://www.duocircle.com/products/route/) ## Pages - [Home](https://www.duocircle.com/) - [Compare](https://www.duocircle.com/compare/) - [Customers](https://www.duocircle.com/case-study/) - [Partners](https://www.duocircle.com/partners/) ## Resources - [Resources](https://www.duocircle.com/resources/) - [About](https://www.duocircle.com/about-us/) - [Contact](https://www.duocircle.com/contact/) - [Legal](https://www.duocircle.com/legal/) - [Transparent Pricing](https://www.duocircle.com/transparent-pricing/) - [Trust Center](https://trust.duocircle.com/) - [Status](https://status.duocircle.com) ## Blog ### Foundational - [What Is Emailpond? Email Warmup And Sender Reputation](https://www.duocircle.com/blog/what-is-emailpond-email-warmup-and-sender-reputation/): Discover what Emailpond is, how email warmup works, and how it helps build sender reputation, improve deliverability, and keep emails out of spam folders. - [What Is URL Manipulation and URL Rewriting? A Complete Guide](https://www.duocircle.com/blog/what-is-url-manipulation-and-url-rewriting-a-complete-guide/): Learn how URL manipulation and URL rewriting work, their key differences, common techniques, security risks, and best practices for managing URLs effectively. - [Shared Email Accounts: Security Risks and How to Avoid Them](https://www.duocircle.com/blog/shared-email-accounts-security-risks-and-how-to-avoid-them/): Shared email accounts can create security risks such as weak passwords, poor accountability, and unauthorized access. Learn safer ways to secure shared inboxes. - [Password Threats: How Stolen Credentials Put Business Email At Risk](https://www.duocircle.com/blog/password-threats-how-stolen-credentials-put-business-email-at-risk/): Password threats can expose stolen credentials, compromise business email, enable account takeovers, and increase the risk of phishing, fraud and data breaches. - [Can A DNS Audit Detect Unauthorized Email Senders?](https://www.duocircle.com/blog/can-a-dns-audit-detect-unauthorized-email-senders/): A DNS audit can identify unauthorized email senders by reviewing SPF, DKIM, DMARC, and MX records for outdated, misconfigured, or suspicious sending sources. - [Domain Records Lookup: A Guide To DNS And Email Authentication](https://www.duocircle.com/blog/domain-records-lookup-a-guide-to-dns-and-email-authentication/): Learn how domain records lookup works to check DNS, SPF, DKIM, and DMARC records, troubleshoot email authentication issues, and improve email security. - [From Website To Inbox: How Consistent Brand Messaging Builds Trust In Customer Communications](https://www.duocircle.com/blog/from-website-to-inbox-consistent-brand-messaging-builds-customer-trust/): Discover how consistent brand messaging from website to inbox builds customer trust, strengthens credibility, and delivers a seamless communication experience. - [Email Sign-Offs That Help Recipients Verify And Act On Business Messages](https://www.duocircle.com/blog/email-sign-offs-help-recipients-verify-act-on-business-messages/): Discover how effective email sign-offs help recipients verify business messages, build trust, and take the right action with confidence. - [VOIP Spoofing: How It Works And How To Protect Your Business](https://www.duocircle.com/blog/voip-spoofing-how-it-works-and-how-protect-your-business/): Learn how VoIP spoofing works, the risks it creates for businesses, and practical ways to detect, prevent, and protect your organization from spoofed calls. - [Email Sender Verification: What The Blue Check Mark Really Means](https://www.duocircle.com/blog/email-sender-verification-what-the-blue-check-mark-really-means/): Email sender verification explains what the blue check mark means, how it confirms sender identity, and why verified emails can improve trust and security. ### Intermediate - [How To Evaluate A Software Development Partner Before Signing A Long-Term Contract](https://www.duocircle.com/blog/how-to-evaluate-software-partner-before-signing-long-term-contract/): Discover how to assess a software development partner’s expertise, communication, pricing, and reliability before signing a long-term contract. - [How Sparkpost Custom Bounce Domains Affect SPF Authentication](https://www.duocircle.com/blog/how-sparkpost-custom-bounce-domains-affect-spf-authentication/): Learn how SparkPost custom bounce domains affect SPF authentication, improve email deliverability, support DMARC alignment, and strengthen sender reputation. - [DMARC Adoption Is Rising. Is Protection Keeping Up?](https://www.duocircle.com/blog/dmarc-adoption-is-rising-is-protection-keeping-up/): Discover why rising DMARC adoption may not ensure email security. Learn how to prevent domain spoofing and strengthen email authentication. - [The Email Breach Bill Is Bigger Than The Stolen Money](https://www.duocircle.com/blog/the-email-breach-bill-is-bigger-than-the-stolen-money/): Email breaches cost more than stolen funds, exposing businesses to reputational damage, regulatory fines, recovery expenses, and lasting customer trust issues. - [Improving Facility Management CMMS Use For Compliance Outcomes](https://www.duocircle.com/blog/improving-facility-management-cmms-use-for-compliance-outcomes/): Learn how facility management CMMS can improve compliance with standardized inspections, corrective actions, preventive maintenance, recordkeeping, and audits. - [How To Plan An Active Directory Migration Without Disruption](https://www.duocircle.com/blog/how-to-plan-an-active-directory-migration-without-disruption/): Plan a smooth Active Directory migration with careful preparation, risk management, backups, testing, and step-by-step execution to minimize disruption. - [How to Fix SPF Softfail: Domain Does Not Designate IP as Permitted Sender](https://www.duocircle.com/blog/how-to-fix-spf-softfail-domain-does-not-designate-ip/): Learn how to fix SPF softfail errors, identify unauthorized sending IPs, update SPF records, and improve email authentication with SPF, DKIM, and DMARC. - [Campaign Monitor SPF: How To Configure And Verify Email Authentication](https://www.duocircle.com/blog/campaign-monitor-spf-how-to-configure-and-verify-email-authentication/): Configure and verify your Campaign Monitor SPF record to authenticate email, improve deliverability, prevent spoofing, and protect your domain reputation. - [The Security Gaps That Appear When Sales Teams Expand Across Borders](https://www.duocircle.com/blog/the-security-gaps-appear-when-sales-teams-expand-across-borders/): Discover the security gaps that emerge as sales teams expand globally, from data exposure and access risks to phishing threats and compliance challenges. - [How To Build A Cybersecurity Team That Protects Email In The Cloud](https://www.duocircle.com/blog/how-to-build-a-cybersecurity-team-to-protect-cloud-email/): Build a cybersecurity team that protects cloud email, prevents cyber threats, secures data, and strengthens your organization’s overall security posture. ### Advanced - [How OEM Anti-Phishing Detects Spoofed Domains And Malicious Email Links](https://www.duocircle.com/blog/how-oem-anti-phishing-detects-spoofed-domains-malicious-email-links/): Learn how OEM anti-phishing solutions detect spoofed domains and malicious email links to prevent phishing attacks, protect users and strengthen email security. - [12 DNS Scanning Techniques for Domain Intelligence and Email Security](https://www.duocircle.com/blog/12-dns-scanning-techniques-for-domain-intelligence-and-email-security/): Discover 12 DNS scanning techniques to improve domain intelligence, identify risks, strengthen email security, and protect your organization from threats. - [9 SMTP Authentication Hardening Techniques To Protect Mail Servers From Abuse](https://www.duocircle.com/blog/9-smtp-authentication-hardening-techniques-protect-mail-servers-from-abuse/): Strengthen email security with these 9 SMTP authentication hardening techniques to protect mail servers from abuse, spam, phishing, and unauthorized access. - [How To Build An Email Infrastructure Monitoring Dashboard That Actually Prevents Outages](https://www.duocircle.com/blog/how-build-email-infrastructure-monitoring-dashboard-that-actually-prevents-outages/): Email remains one of the most critical communication channels for modern businesses. - [DKIM For Multi-Tenant SaaS: Email Authentication Best Practices](https://www.duocircle.com/blog/dkim-deployment-multitenant-saas-platforms-secure-email-authentication-best-practices/): Learn DKIM deployment best practices for multi-tenant SaaS platforms. Improve email security, prevent spoofing, and ensure trusted email authentication. - [Mail Server Authentication Strategies For High-Volume Email Senders](https://www.duocircle.com/blog/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. - [10 DKIM Key Rotation Checklist Mistakes That Break Email Deliverability](https://www.duocircle.com/blog/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. - [Office 365 Migration: Security Risks To Avoid With Sensitive Data](https://www.duocircle.com/blog/office-365-migration-solution-security-risks-avoid-sensitive-business-data/): Avoid costly security risks during an Office 365 migration solution. Protect sensitive business data with best practices for secure migration. ### Recent Articles (50 most recent of 1405 total) - [6 Best Frontline Training Platforms for Workplace Skills](https://www.duocircle.com/blog/6-best-frontline-training-platforms-for-workplace-skills/) - [How To Evaluate A Software Development Partner Before Signing A Long-Term Contract](https://www.duocircle.com/blog/how-to-evaluate-software-partner-before-signing-long-term-contract/) - [Ivanti VPN Backdoor, Microsoft Patch Tuesday, Backup Servers Hijacked – Cybersecurity News [October 12, 2026]](https://www.duocircle.com/blog/cybersecurity-news-update-week-42-of-2026/) - [How Sparkpost Custom Bounce Domains Affect SPF Authentication](https://www.duocircle.com/blog/how-sparkpost-custom-bounce-domains-affect-spf-authentication/) - [DMARC Adoption Is Rising. Is Protection Keeping Up?](https://www.duocircle.com/blog/dmarc-adoption-is-rising-is-protection-keeping-up/) - [How OEM Anti-Phishing Detects Spoofed Domains And Malicious Email Links](https://www.duocircle.com/blog/how-oem-anti-phishing-detects-spoofed-domains-malicious-email-links/) - [What Is Emailpond? Email Warmup And Sender Reputation](https://www.duocircle.com/blog/what-is-emailpond-email-warmup-and-sender-reputation/) - [What Is URL Manipulation and URL Rewriting? A Complete Guide](https://www.duocircle.com/blog/what-is-url-manipulation-and-url-rewriting-a-complete-guide/) - [The Email Breach Bill Is Bigger Than The Stolen Money](https://www.duocircle.com/blog/the-email-breach-bill-is-bigger-than-the-stolen-money/) - [Yahoo Phishing Report Email: How To Identify And Report Suspicious Messages](https://www.duocircle.com/blog/yahoo-phishing-report-email-how-identify-and-report-suspicious-messages/) - [How To Troubleshoot Zendesk DKIM Configuration Mismatches In DNS](https://www.duocircle.com/blog/how-to-troubleshoot-zendesk-dkim-configuration-mismatches-in-dns/) - [Cisco SD-WAN Vulnerability, Citrix Zero-Days, SharePoint Ransomware Risk – Cybersecurity News [October 05, 2026]](https://www.duocircle.com/blog/cybersecurity-news-update-week-41-of-2026/) - [Improving Facility Management CMMS Use For Compliance Outcomes](https://www.duocircle.com/blog/improving-facility-management-cmms-use-for-compliance-outcomes/) - [Why Gmail Rejects Emails After A Mail Server Migration: SMTP Errors And Fixes](https://www.duocircle.com/blog/gmail-rejects-emails-after-mail-server-migration-smtp-errors-fixes/) - [Shared Email Accounts: Security Risks and How to Avoid Them](https://www.duocircle.com/blog/shared-email-accounts-security-risks-and-how-to-avoid-them/) - [How To Plan An Active Directory Migration Without Disruption](https://www.duocircle.com/blog/how-to-plan-an-active-directory-migration-without-disruption/) - [Password Threats: How Stolen Credentials Put Business Email At Risk](https://www.duocircle.com/blog/password-threats-how-stolen-credentials-put-business-email-at-risk/) - [Can A DNS Audit Detect Unauthorized Email Senders?](https://www.duocircle.com/blog/can-a-dns-audit-detect-unauthorized-email-senders/) - [Linux Kernel Vulnerabilities, Critical Authlib Bypass, 500,000 Secrets Exposed – Cybersecurity News [September 28, 2026]](https://www.duocircle.com/blog/cybersecurity-news-update-week-40-of-2026/) - [Domain Records Lookup: A Guide To DNS And Email Authentication](https://www.duocircle.com/blog/domain-records-lookup-a-guide-to-dns-and-email-authentication/) - [From Website To Inbox: How Consistent Brand Messaging Builds Trust In Customer Communications](https://www.duocircle.com/blog/from-website-to-inbox-consistent-brand-messaging-builds-customer-trust/) - [How to Fix SPF Softfail: Domain Does Not Designate IP as Permitted Sender](https://www.duocircle.com/blog/how-to-fix-spf-softfail-domain-does-not-designate-ip/) - [Online PTR Lookup: How To Check IPV4 And IPV6 Reverse DNS](https://www.duocircle.com/blog/online-ptr-lookup-how-check-ipv4-and-ipv6-reverse-dns/) - [Email Sign-Offs That Help Recipients Verify And Act On Business Messages](https://www.duocircle.com/blog/email-sign-offs-help-recipients-verify-act-on-business-messages/) - [Spamexperts Outgoing SPF: How To Configure SPF For Outbound Email](https://www.duocircle.com/blog/spamexperts-outgoing-spf-how-to-configure-spf-for-outbound-email/) - [Bitget Crypto Heist, AI Bypasses Controls, NetScaler Flaws Exploited – Cybersecurity News [September 21, 2026]](https://www.duocircle.com/blog/cybersecurity-news-update-week-39-of-2026/) - [How To Configure An SPF Record For Rackspace Email](https://www.duocircle.com/blog/how-to-configure-an-spf-record-for-rackspace-email/) - [How to Configure SPF and DKIM for IONOS Email](https://www.duocircle.com/blog/how-to-configure-spf-and-dkim-for-ionos-email/) - [VOIP Spoofing: How It Works And How To Protect Your Business](https://www.duocircle.com/blog/voip-spoofing-how-it-works-and-how-protect-your-business/) - [How To Configure Qualtrics SPF: A Step-By-Step Guide To Setting Up Your SPF Record](https://www.duocircle.com/blog/configure-qualtrics-spf-step-by-step-guide-setting-spf-record/) - [ShinyHunters DMV Leak, Cisco Fixes Zero-Day, Cyberattack Ship Tracking – Cybersecurity News [September 14, 2026]](https://www.duocircle.com/blog/cybersecurity-news-update-week-38-of-2026/) - [Email Sender Verification: What The Blue Check Mark Really Means](https://www.duocircle.com/blog/email-sender-verification-what-the-blue-check-mark-really-means/) - [Authoritative vs. Recursive DNS: Understanding the Key Differences](https://www.duocircle.com/blog/authoritative-vs-recursive-dns-understanding-the-key-differences/) - [Campaign Monitor SPF: How To Configure And Verify Email Authentication](https://www.duocircle.com/blog/campaign-monitor-spf-how-to-configure-and-verify-email-authentication/) - [Microsoft Patch Tuesday, CISA Adds Flaws, Revolut Data Breach – Cybersecurity News [September 07, 2026]](https://www.duocircle.com/blog/cybersecurity-news-update-week-37-of-2026/) - [Hotmail DNS Records: SPF, DKIM & DMARC Setup Guide](https://www.duocircle.com/blog/hotmail-dns-records-spf-dkim-dmarc-setup-guide/) - [How To Add DKIM Public Key In DNS Cpanel: Step-By-Step Setup Guide](https://www.duocircle.com/blog/how-to-add-dkim-public-key-dns-cpanel-setup-guide/) - [The Security Gaps That Appear When Sales Teams Expand Across Borders](https://www.duocircle.com/blog/the-security-gaps-appear-when-sales-teams-expand-across-borders/) - [Why Are My Emails Bouncing? Common Causes and How to Fix Them](https://www.duocircle.com/blog/why-are-emails-bouncing-common-causes-and-how-to-fix/) - [Constant Contact SPF Record: How To Set Up And Verify It](https://www.duocircle.com/blog/constant-contact-spf-record-setup-and-verification-guide/) - [NetSuite SPF Record: How Configure, Validate And Troubleshoot](https://www.duocircle.com/blog/netsuite-spf-record-how-configure-validate-and-troubleshoot/) - [Berlin Ransomware Theft, Eastlink Data Breach, Dark Web Exposure – Cybersecurity News [August 31, 2026]](https://www.duocircle.com/blog/cybersecurity-news-update-week-36-of-2026/) - [How to Set Up SPF and DKIM for Campaign Monitor](https://www.duocircle.com/blog/how-to-set-up-spf-and-dkim-for-campaign-monitor/) - [URL Blacklist Explained: How Email Security Systems Block Malicious Links](https://www.duocircle.com/blog/url-blacklist-explained-how-email-security-systems-block-malicious-links/) - [Network Solutions SPF Record: How To Add And Configure SPF](https://www.duocircle.com/blog/network-solutions-spf-record-how-to-add-and-configure-spf/) - [12 DNS Scanning Techniques for Domain Intelligence and Email Security](https://www.duocircle.com/blog/12-dns-scanning-techniques-for-domain-intelligence-and-email-security/) - [Why I Moved My Company Email Off Google After Seven Years](https://www.duocircle.com/blog/why-i-moved-company-email-from-google-after-seven-years/) - [ShinyHunters Target McKesson, Boston Scientific Cyberattack, Hasbro Breach Disclosed – Cybersecurity News [August 24, 2026]](https://www.duocircle.com/blog/cybersecurity-news-update-week-35-of-2026/) - [How To Build A Cybersecurity Team That Protects Email In The Cloud](https://www.duocircle.com/blog/how-to-build-a-cybersecurity-team-to-protect-cloud-email/) - [6 Effective Data Loss Prevention Strategies for Business Email Security](https://www.duocircle.com/blog/6-effective-data-loss-prevention-strategies-for-business-email-security/) > Full archive: 1405 posts indexed in [the sitemap](https://www.duocircle.com/sitemap-index.xml). ## Optional - [Privacy](https://www.duocircle.com/legal/privacy/) - [Terms](https://www.duocircle.com/legal/cloud-terms/)