DomainKeys Identified Mail (DKIM) is a well-established email authentication protocol designed to help organizations defend against email spoofing, phishing attacks, and business email compromise (BEC). When implemented correctly, DKIM authentication allows the recipient’s email server to verify that a signed email has genuinely originated from the stated domain and that its message content has not been tampered with during transit.
Sender Policy Framework (SPF) is a core email authentication protocol designed to enhance email security. SPF records play a crucial role in protecting domains from phishing, spoofing, and impersonation attacks by specifying which mail servers are authorized to send on behalf of a domain. When properly configured, SPF authentication significantly improves deliverability, helping emails avoid spam folders used by providers such as Gmail and Yahoo.
SPF records updated by Google: Here’s what domain owners need to know!
by DuoCircle
Does your SPF record include Google as an authorized sender? If yes, then you must be dependent on Google’s recommended ‘include:_spf.google.com’ entry to make the most out of the SPF protocol. Recently, this entry has been updated by Google. So, if your domain has outdated or custom configurations, then the latest update may cause certain issues. This blog aims to explore the update in detail and the tactics that can be used to avoid any potential email deliverability hassles.
What is MTA-STS (Mail Transfer Agent Strict Transport Security) and why do you need it?
by DuoCircle
We have heard so much about securing your outgoing emails, but the truth is, attackers can even enter your digital ecosystem through emails that are sent to your organization. This means your incoming emails are just as unsafe as your outbound ones.
DomainKeys Identified Mail (DKIM) is one of the most robust email authentication methods, helping organizations defend against email spoofing, phishing, and spam. By using cryptographic digital signatures and distributing public keys through DNS records, DKIM verifies that outgoing emails are authorized and tamper-free, which is critical for brand protection and maintaining user trust.
Cyber incidents this week hit emergency alerting, e-commerce, infrastructure, and app stacks. To start with, ransomware against the CodeRED platform disrupted local emergency notifications and exposed clear-text passwords. In another incident, a five-month breach at a major East Asian retailer affected tens of millions of customer accounts. Attackers exploited a command injection bug in Array Networks gateways, an admin takeover flaw in the King Addons WordPress plugin, and the React2Shell RCE vulnerability in React and Next.js.
Google Workspace helps businesses send emails every day, but keeping those emails safe is just as important as sending them. Gmail now strongly encourages domains to use DMARC, which tells mail servers how to treat suspicious messages. If you set it up correctly, your emails are more likely to reach inboxes and your brand stays protected.
Selecting a reliable partner for your email migration is a mission-critical decision for both individuals and organizations, whether you are overseeing a personal email migration, business email migration, or a large-scale enterprise email migration.
DomainKeys Identified Mail (DKIM) is a sophisticated email authentication protocol used to help combat email spoofing and to ensure message integrity between the email sender and the email recipient. At its core, DKIM works by adding a unique cryptographic digital signature—known as the DKIM signature—to every outgoing email. This DKIM signature is generated using a private DKIM key, which is securely stored by the email server or email sending platform.
DMARC (Domain-based Message Authentication, Reporting, and Conformance) is a crucial email security protocol that prevents email spoofing, phishing attacks, and business email compromise by ensuring that only authorized sources can send email on behalf of a domain. By leveraging SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail), DMARC builds on these foundational email authentication methods to provide domain owners with granular control and visibility over their email traffic.
The Difference Between ~all, -all, and +all in SPF
by DuoCircle
SPF is the foundation of your email authentication, as it tells the receiving servers, “these are the only servers and addresses allowed to send emails on our behalf.” So, when an email goes out from your side to a provider like Gmail or Microsoft Outlook, their servers pull out your SPF record to confirm if the email came from a server you actually approved. If the server matches one of the entries in the list, the email is delivered.
Cyber incidents this week included ToddyCat deploying new tools to steal email data, Harvard reporting a breach affecting its alumni community, and a vendor compromise at SitusAMC exposing corporate records tied to major banks. Alongside, Asahi confirmed data theft affecting two million individuals, and OpenAI disclosed limited user information exposure linked to a Mixpanel breach. Here are this week’s top headlines.
You might have been sending emails using Gmail for years now, but that’s not a good enough reason for the Email Service Provider (ESP) to let your email in, even if it feels like something’s off. Since email-based attacks are becoming so frequent and rampant, your sender reputation and good faith no longer suffice, given today’s threat landscape. That is why Gmail and other ESPs verify every email they receive before delivering it to the recipient’s inbox.
How cybercriminals use DNS hijacking to bypass DMARC policies
by DuoCircle
Email authentication protocols like SPF, DKIM, and DMARC are supposed to stop attackers from pretending to be you and dupe your clients. But what if they target the very system that these protocols depend on?
Logitech Data Breach, Mass Router Hijack, Android Trojan Sturnus – Cybersecurity News [November 17, 2025]
by DuoCircle
Here are this week’s cybersecurity updates, bringing you headlines that made news around the world. Princeton University reported a data breach impacting alumni and donors, and the Clop extortion gang’s activity continued, with Logitech confirming data theft linked to a third-party zero-day.
DuoCircle, LLC (“Company”) hereby provides formal notice that all data associated with the discontinued MailHostingService.com email hosting platform has been permanently and irreversibly destroyed in accordance with applicable data protection regulations and industry best practices.
Gmail enforcement norms for non-compliant emails: What’s new in 2025?
by DuoCircle
Email-based cyberattacks have become so severe and rampant that you can no longer afford to make email security an afterthought. Attackers out there are ready to seize even the most seemingly insignificant vulnerabilities at every chance they get. If your outgoing emails are not protected with email authentication protocols like SPF, DKIM, and DMARC, you are essentially making it easier for attackers to steal your confidential data, deceive your customers, and install malware on their systems.
How email authentication helps you prove sender identity under ISO 27001
by DuoCircle
Email is one of the main ways companies talk to customers, partners, and even their own teams. Because it is used so much, it also becomes an easy target for attackers who try to pretend to be someone else or steal important information. When a business wants to follow ISO 27001, it needs to show that its messages are safe and really coming from the right sender. That is where email authentication becomes helpful.
Cybersecurity headlines this week show a clear picture, and no one seems immune. Hyundai confirmed a data breach that may have exposed millions of Social Security numbers, and Google has gone on the offensive, suing a China-based group accused of running a billion-dollar phishing operation.
What happens when you misconfigure DKIM for your domain?
by DuoCircle
Your outgoing emails are only as safe as the configuration of your authentication protocols, like DKIM or DomainKeys Identified Mail. We say this because your emails are not inherently secure, which means anyone can intercept your outgoing emails and try to alter or impersonate them before they reach your recipients. This happens when you have not implemented DKIM at all or configured it incorrectly.
![React2Shell RCE Threat, CodeRED Alert Disruption, Coupang Data Breach – Cybersecurity News [December 01, 2025]](https://www.duocircle.com/wp-content/uploads/2025/12/spf-record-generator-4560.jpg)
![ToddyCat APT Evolving, Harvard Breach Reported, SitusAMC Vendor Breach– Cybersecurity News [November 24, 2025]](https://www.duocircle.com/wp-content/uploads/2025/12/spf-validator-5634.jpg)
![Logitech Data Breach, Mass Router Hijack, Android Trojan Sturnus – Cybersecurity News [November 17, 2025]](https://www.duocircle.com/wp-content/uploads/2025/11/hosted-email-server-4002.jpg)
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