Email security threats remain a primary risk for enterprises because email still sits at the center of communication, business transactions, and critical workflows. That reliance makes the inbox a practical entry point for fraud, account compromise, and data exposure.

This article examines the most prevalent email threats facing enterprises and the defense strategies that can help reduce risk.

This article draws from insights shared in "Five Email Threats to Watch for in 2026" at Abnormal Innovate. Watch recording for expert breakdowns of these attacks with live case studies.

• Identity has become the new payload, with attackers focusing on compromising people and entities rather than delivering traditional malicious files.

• Multistage attacks that build trust before delivering payloads are replacing single-step phishing attempts.

• OAuth consent phishing can evade password-based controls by stealing tokens instead of passwords.

• Defense in depth combined with Abnormal behavioral AI can help strengthen protection against evolving email threats.

Email security threats use email as an entry point to compromise organizations, steal data, or execute fraud.

Unlike cold outreach through other channels, email conversations carry inherent credibility. When someone replies within an existing thread, even if that thread was fabricated, recipients often trust the legitimacy of the exchange.

A key shift in modern attacks centers on identity. Traditional threats delivered malware through attachments or malicious links. Today's sophisticated attacks often use a trusted identity to target others across the organization and its vendor network.

As Piotr Wojtyla, Head of Detection and Platform at Abnormal, explains in the webinar: "The identity, the person, the vendor, the entity you're interacting with is the payload."

This shift has major implications. Account takeover can expose one inbox and give attackers a trusted platform to target others in the compromised user's contact list.

Email remains central to SaaS identity and business workflows.

Compromising a single email account often unlocks access to a broader cloud ecosystem, including CRM platforms, financial systems, collaboration tools, and sensitive data repositories.

Attackers constantly adapt techniques to exploit emerging trends, and security tools often lag behind those changes. The interconnected nature of cloud environments amplifies this challenge. Single sign-on and OAuth integrations mean one compromised credential can expand into broader organizational access. Attackers target email because it often serves as a starting point into that connected environment.

Traditional secure email gateway (SEG) solutions were designed for a different threat landscape, one where malicious payloads and known bad senders could be identified through signatures and reputation. Modern attacks often use legitimate infrastructure and trusted identities, which can reduce the effectiveness of those controls on their own.

Phishing and spear phishing remain effective because attackers tailor messages to the recipient and the moment.

Phishing casts a wide net, sending generic malicious messages to many recipients in hopes that some will click. Spear phishing takes a targeted approach, researching specific individuals and crafting personalized messages designed to deceive them.

Attackers may also establish legitimacy before asking for action. They might initiate a seemingly innocent conversation, exchange several messages, and only introduce the payload once the recipient feels comfortable.

This approach can defeat security tools that analyze individual messages in isolation. Effective defense can combine user training with Abnormal behavioral AI for email-borne threats, helping teams identify unusual patterns across conversation threads rather than reviewing messages one by one.

QR code phishing becomes more convincing when it is embedded in what looks like a normal business exchange.

QR code phishing gained traction because QR codes can move the interaction to a mobile device outside the protected corporate environment, where endpoint security and web filters may offer less protection.

Attackers may submit legitimate-looking inquiries through an organization's website contact form, then wait for a genuine response. When the organization replies, attackers continue the conversation and eventually send a QR code supposedly containing documents related to a business proposal.

Because the victim initiated the conversation, the request can feel routine. Training users to verify QR code sources through alternative channels before scanning remains important, and email defenders can benefit from reviewing the full conversation history around these requests.

Business email compromise (BEC) targets payment and account-change workflows directly.

Business email compromise attacks impersonate executives, vendors, or colleagues to manipulate financial processes. Unlike phishing that steals credentials, BEC directly targets monetary theft through fraudulent wire transfers, invoice manipulation, or payroll changes.

AI has transformed BEC effectiveness. Piotr Wojtyla notes: "The emails are perfectly written. The grammar is spot on. There are no more obvious mistakes. The information embedded in the email follows specific process of an organization."

Gone are the grammatical errors and awkward phrasing that once helped recipients identify fraudulent messages. AI-generated content can match organizational tone, reference real processes, and include details that suggest insider knowledge.

Out-of-band verification, confirming requests through a separate communication channel like a phone call to a known number, remains one of the most reliable defenses for financial transactions.

Spoof thread vendor impersonation uses fabricated conversation history to make a false request look preapproved.

This technique involves attackers creating fabricated email threads that appear to show an ongoing conversation. These fake threads include personalized information about organizational processes, authorization requirements, and payment procedures.

The fabricated history often names actual authorized personnel, creating the impression that proper approvals have already occurred. Recipients see what looks like a legitimate conversation thread with their colleague authorizing a payment change, even though the entire exchange was manufactured by attackers.

Defending against spoof thread vendor impersonation can require context-rich analysis of sender patterns and message history.

OAuth consent phishing shifts the attack from password theft to application access.

OAuth consent phishing represents a shift from credential theft to token theft. Rather than stealing passwords, attackers trick users into granting permissions to malicious applications, and those permissions can persist until they are explicitly revoked.

A common delivery method involves Microsoft Teams invitations containing links to OAuth consent screens. The link itself uses legitimate Microsoft infrastructure, making it harder to detect. Once a user grants consent, attackers can gain persistent access that may evade password-based MFA protections.

Organizations can reduce exposure through SSPM guide by configuring Microsoft 365 to require administrator approval before users can consent to applications. This configuration change can make OAuth consent phishing harder to execute successfully.

Lateral phishing spreads from a compromised account, which makes the sender appear familiar and credible.

Lateral phishing leverages compromised accounts to attack others from trusted infrastructure. Once attackers control an account, they access the victim's contact list and send malicious messages that appear to come from a known sender.

This technique can spread from one organization to another through vendor and partner relationships. A compromised account at a supplier can target multiple customer organizations, all receiving malicious messages from an address they have communicated with before.

AI-powered payroll fraud makes routine change requests look legitimate and urgent.

AI dramatically enhances payroll fraud attacks by generating personalized messages that follow organization-specific processes. Attackers extract information from compromised accounts and quickly turn those details into convincing requests.

These attacks target payroll departments with requests to update direct deposit information, change tax withholdings, or modify employee records. The messages reference real employees, actual pay periods, and legitimate HR procedures.

Multi-person authorization for payroll or financial changes provides an important control. Requiring two or more individuals to approve changes makes it harder for attackers to execute fraud with a single compromised account.

Most enterprise email security gaps come from control limitations, operational overload, and preventable configuration weaknesses.

• Over-Reliance on Legacy Controls: Traditional email gateways may miss attacks that use legitimate infrastructure and contain no obvious malicious indicators.

• Alert Fatigue: Security teams drowning in false positives may miss genuine threats or become desensitized to warnings.

• Inconsistent User Training: Sporadic awareness programs fail to build the recognition needed to spot sophisticated attacks.

• Configuration Gaps: Default settings in Microsoft 365 and other platforms often allow behaviors attackers exploit, including unrestricted application consent.

These challenges often compound one another, increasing risk even when organizations have multiple controls in place.

Reducing email risk requires layered controls, stronger configuration hygiene, and user preparation.

• Implement Defense in Depth: Multiple security layers ensure that when one control fails, others remain. The more attacks you can prevent upfront, the less time you spend on incident response.

• Deploy Abnormal Behavioral AI: Abnormal's behavioral AI is designed to understand patterns across users, vendor interactions, timing, and engagement flows, helping teams spot suspicious email activity that rule-based systems may miss. It can also enhance existing email defenses rather than replace a layered approach.

• Harden Configurations with SSPM: Identifying and remediating misconfigurations can reduce exposure to entire attack categories. Restricting user consent for applications can make OAuth consent phishing harder to execute.

• Elevate Users as Defenders: Users are a key line of defense. Simulations, real examples, and regular training can help them build stronger recognition skills.

Together, these practices can help organizations reduce exposure without relying on a single control.

Modern email threats increasingly rely on trust, identity abuse, and social engineering. Organizations can strengthen defenses by pairing layered controls with configuration hardening, user preparation, and better visibility into suspicious email activity.

Want to see how these email threats are evolving in real-time? Watch our expert breakdown of the five email attacks to watch in 2026, including live case studies and detection strategies, at Abnormal Innovate.

Ready to assess your organization's resilience against modern email threats? Request a demo to see how behavioral AI detects attacks that can bypass traditional security controls.