The Simple Mail Transfer Protocol (SMTP) is the foundational email protocol responsible for the reliable delivery of outbound email across the internet. Pioneered by Ray Tomlinson, SMTP governs the communication between email clients and email servers—or between servers themselves—in the process known as the SMTP session. In this session, the SMTP client initiates a connection to an SMTP daemon running on the outgoing mail server, typically on an SMTP port such as port 25, port 587, or port 465.
Configuring SPF, DKIM, and DMARC for Loops.so: A guide
by DuoCircle
Sending out email campaigns isn’t just about crafting nice-looking emails; they should also be authenticated and secure. So, whether you are sending these emails directly from your mailbox or using an external email platform like Loops, you need to ensure that the receiving servers trust your emails and that they are delivered securely to the recipient’s inbox.
The Sender Policy Framework (SPF) is a critical component of contemporary email authentication strategies aimed at combatting email spoofing and enhancing email fraud prevention. SPF functions by enabling domain owners to specify, through DNS TXT records, the mail servers authorized to send emails on their behalf. This specification is embedded in the SPF record syntax, which is implemented within DNS records and interpreted by receiving mail servers during an SPF check.
Cyber threats kept security teams busy this week. A new campaign called PassiveNeuron is spying on government and industry networks across several regions, while the Jingle Thief group is running cloud-based gift card scams.Hackers are also exploiting the SessionReaper bug in Adobe Commerce, and a critical Lanscope flaw has been flagged by CISA. In healthcare, a breach at Conduent exposed personal data from 462,000 Blue Cross Blue Shield members, underscoring how widespread and damaging these attacks have become. Here are the latest updates from this past week.
Shop till you drop while staying protected from scams this Black Friday
by DuoCircle
The Black Friday week is undeniably the best time to shop, grab great deals, and perhaps save a few bucks. But this is only until you lose more than you bargained for; your personal data, payment details, or even your hard-earned money, to a well-crafted cyber attack.
The X-Google-DKIM-Signature is a specialized email header inserted by Gmail’s email servers during the process of message transmission within Google’s ecosystem. It is a variant of the standard DKIM (DomainKeys Identified Mail) signature, tailored to Google’s email authentication processes. This header serves as a cryptographic token that verifies the message’s authenticity and integrity using public key cryptography techniques. By generating and appending the X-Google-DKIM-Signature, Gmail ensures that outbound messages are protected against malicious practices like email spoofing and tampering.
DomainKeys Identified Mail (DKIM) is a cornerstone of modern email authentication frameworks, designed to bolster email security by verifying the authenticity and integrity of email messages. It operates by enabling a sender to affix a cryptographic signature, known as a digital signature, within the email headers. This signature is derived through public key cryptography, ensuring that recipients can verify the identity of the sender and confirm that the email content remains unaltered during transit.
How does DMARC prevent malware distribution via spoofed emails?
by DuoCircle
Not all fraudulent emails redirect you to a different link or ask you to fill in your sensitive information; some even make you download attachments or embedded files that are infected with malware.
It’s been a hectic week for enterprise security, with several major companies pushing out critical fixes. F5 admitted that attackers stole its BIG-IP source code, which even triggered a federal emergency directive. Microsoft wasn’t far behind, releasing 183 patches, including three zero-days, just as Windows 10 support was ending, and it had to tighten security on Edge’s IE mode after reports of it being exploited. On top of that, successive flaws struck Oracle’s E-Business Suite, and Cisco devices were hit by a new campaign called Operation Zero Disco that used a zero-day exploit to deploy stealthy Linux rootkits.
Office 365 migration, particularly tenant-to-tenant migration within Microsoft 365 environments, is a critical process that organizations undertake during mergers, acquisitions, or restructuring. This cloud migration involves the complex movement of data, identities, and permissions from one Office 365 tenant to another, ensuring retention of data integrity and continuity in cloud collaboration.
![Silent PassiveNeuron Attacks, Jingle Thief Fraud, SessionReaper Adobe Exploit – Cybersecurity News [October 20, 2025]](https://www.duocircle.com/wp-content/uploads/2025/10/spf-validator-7800.jpg)
![F5 Breach Response, Windows 10 Patch, Oracle Security Flaws – Cybersecurity News [October 13, 2025]](https://www.duocircle.com/wp-content/uploads/2025/10/dkim-validation-5602.jpg)
