DomainKeys Identified Mail (DKIM) is a critical component of modern email authentication frameworks designed to enhance email security by verifying sender identities and ensuring message integrity. Introduced as an open standard and formalized by RFC 6376, DKIM employs public key cryptography to cryptographically sign email headers and message body, allowing mailbox providers like Google’s Gmail, Microsoft 365, and Yahoo to verify that emails originate from legitimate senders.
Troubleshooting SPF syntax errors: Tips for fixing the most common mistakes
by DuoCircle
When you configure SPF for your domain, there are a lot of things that can go wrong and wreck your entire setup. And if your SPF configuration is not done right, your emails will be at risk, the risk of being rejected, marked as spam, or worse, being impersonated by threat actors.
An online SMTP server functions as a critical component of the email protocol infrastructure, facilitating the transfer of outgoing emails over the internet. SMTP, or Simple Mail Transfer Protocol, is the standardized protocol that governs how email servers, or mail transfer agents (MTAs), communicate to ensure reliable email delivery. Acting as an outgoing mail server, an SMTP server handles the sending process, routing emails through SMTP relay channels to the recipient’s email server.
This week saw a wave of cyber incidents across critical sectors. A stealthy campaign used the BRICKSTORM backdoor to hide inside networks for over a year, while a flaw in Pandoc was exploited in attempts to steal AWS credentials. Libraesva patched a bug in its Email Security Gateway that attackers are already abusing. Airports across Europe faced massive disruptions after a ransomware attack, and researchers flagged ShadowV2, a new Docker-targeting botnet offering DDoS-for-hire services.
Email hosting servers constitute the backbone of modern business communication infrastructure. At their core, these servers manage the sending, receiving, and storage of electronic mail by leveraging robust email server software. Their configuration involves the integration of various email protocols such as SMTP (Simple Mail Transfer Protocol), IMAP (Internet Message Access Protocol), and POP3 (Post Office Protocol 3), ensuring smooth mail routing between mail transfer agents (MTAs) and mail delivery agents (MDAs). Businesses depend on these servers to provide reliable communication channels facilitated through inbound mail servers, outbound mail servers, and mailboxes with efficient mailbox storage management.
When DKIM is not properly aligned for your domain, your outgoing emails may be at risk of tampering. That means anyone can make unauthorized changes to your email while it’s on the way to the receiver’s inbox, and the recipient might never even know it was altered.
Sender Policy Framework (SPF) is a critical email authentication protocol that plays a vital role in bolstering email security. Essentially, SPF allows domain owners to specify which mail servers are authorized to send emails on their behalf by publishing specific rules within DNS TXT records. This configuration helps receiving mail servers verify if incoming messages claiming to be from a particular domain are indeed sent from legitimate sources.
Why should you care about DMARC? What happens if you don’t?
by DuoCircle
Apart from the fact that most major email service providers and organizations have made DMARC mandatory, many teams enable it without fully understanding what it does or why it matters.
Cross tenant mailbox migration is a specialized form of tenant to tenant migration within Microsoft 365 environments, involving the transfer of mailboxes, shared mailboxes, public folders, and associated mailbox data between separate Office 365 tenants. This process is critical in multi-tenant environments where enterprises operate multiple Microsoft Exchange Online tenants, often due to mergers, acquisitions, divestitures, or organizational restructuring.
Cyber incidents this week underline just how disruptive attacks have become. One of the country’s biggest carmakers has kept its production lines shut, losing around 1,000 vehicles a day while work continues to restore systems. Investigators also uncovered a vast ad-fraud scheme that ran across 224 apps with 38 million downloads, generating more than two billion fake ad requests daily. Alongside that, a worm-like breach spread through hundreds of npm packages, while poisoned search results and phishing emails delivered remote-access malware to new victims.
![Ransomware Disrupts Airports, BRICKSTORM Backdoor Intrusions, Pandoc Flaw Exploited – Cybersecurity News [September 22, 2025]](https://www.duocircle.com/wp-content/uploads/2025/09/dkim-validation-5601.jpg)
![JLR Cyber Shutdown, SlopAds App Fraud, Worm Hits npm – Cybersecurity News [September 15, 2025]](https://www.duocircle.com/wp-content/uploads/2025/09/spf-permerror-0009.jpg)