What the Data Shows
Misdirected Emails & Human Mistakes
- In a new study by Abnormal AI, surveying over 300 security & IT professionals, 98% say misdirected email (i.e., sending a legitimate email to the wrong recipient) is a “significant risk”, even superseding malware or credential theft in some cases. (FinancialContent)
- In that same report: 96% of organizations reported experiencing data loss or exposure from misdirected email in the past year; 95% say they saw measurable business impact (remediation costs, compliance issues, reputational damage). (Abnormal AI)
- Among other findings:
- 47% of security/IT professionals learn about a misdirected email not via a security tool but because an external recipient or internal team flagged it. (Abnormal AI)
- The report claims misdirected emails accounted for 27% of all data protection incidents under the General Data Protection Regulation (GDPR) in the past year, contributing to over US $1.2 billion in fines globally. (FinancialContent)
Broader Evidence of Human Error as Key Risk
- A survey by Mimecast found that 95% of data breaches in 2024 involved human error (negligent or unintentional employee actions) rather than purely technical failures. (Infosecurity Magazine)
- According to a report from Proofpoint: 74% of CISOs surveyed identify human error as the biggest cybersecurity vulnerability for their organisation (vs. ~60% the prior year). (securityinfowatch.com)
- A 2024/2025 report from Kaspersky Lab indicates that internal staff errors (non-IT workers) account for ~64% of recent cybersecurity incidents. (media.kasperskydaily.com)
Email Specifics: Why Email Is a Key Vector
- An article citing the Kiteworks 2025 “Data Security & Compliance Risk Annual Survey” claims that human error drives 60% of email-related breaches. (FutureCISO)
- Another study by Egress found that among outbound email incidents: wrong recipient or incorrect attachment accounted for ~42% of incident triggers; overall human error triggered ~69% of security prompts. (iaapuk.org)
Why Is Human Error So Prominent in Email?
Here are the contributing factors and dynamics making email human-error risk especially acute:
- Email is old, ubiquitous, and inherently error-prone
- Email protocols were built in an era before modern data-threats; they rely on human addressing, attachments, forwarding, etc. The Kiteworks article notes: “email remains 16% more vulnerable to breaches than more secure transfer protocols”. (FutureCISO)
- Many organisations still rely on traditional Data Loss Prevention (DLP) rules and static filters, which may catch malicious inbound threats but struggle with outbound mis-addressing or mistaken attachments.
- Outbound email is often overlooked
- Organisations heavily invest in inbound threat detection (phishing, malware) but often give less attention to outbound risks (sending sensitive data to wrong recipients). The Abnormal AI report explicitly states that “enterprises have invested heavily in stopping inbound threats … but outbound email remains a major vector for human error — one that has historically been overlooked.” (Abnormal AI)
- The fact that many misdirected email incidents are discovered by recipients rather than security tools (47%) suggests poor visibility and inadequate monitoring of outbound flows. (Abnormal AI)
- Complex human workflows and high volume
- In modern enterprises, employees send large numbers of emails, often under time pressure, multitasking, remote/hybrid environments. Mistakes like selecting the wrong “To” address, forgetting to blind-copy, attaching the wrong file are common.
- The Egress data shows 42% of prompts were triggered by wrong recipient or incorrect attachment. (iaapuk.org)
- Regulatory & reputational stakes are high
- When sensitive or regulated data (PII, PHI, financial information) is mis-sent, the organisation may face compliance violations (e.g., GDPR), fines, customer trust erosion, remediation costs.
- Abnormal AI’s report links misdirected emails to ~US$1.2 billion in fines worldwide. (Abnormal AI)
- Technology alone can’t eliminate human mistakes
- Static rules (DLP, policy-based filtering) often generate many false positives and may not catch contextually valid but mis-addressed emails. The Abnormal report says average enterprises spend over 400 hours per year managing false positive alerts. (Abnormal AI)
- Human behaviour is variable; solutions that only look at metadata (file type, recipient domain) may miss issues like a trusted recipient receiving inappropriate content or a staff member forwarding sensitive content mistakenly.
Consequences & Business Impact
Here are the key risks and impacts tied to human-error in email security:
- Data breaches and exposure: Mis-addressed emails can leak confidential information outside the organisation, leading to breach incidents.
- Regulatory fines: For example, misdirected emails were linked to 27% of GDPR data-protection incidents in one survey. (FinancialContent)
- Reputational damage and client churn: The Egress 2024 report shows in organisations where outbound email breaches occurred, 49% reported damage to client relationships, 22% lost customers. (cyberlogic.co.za)
- Operational & remediation costs: Investigating, notifying, remediating mis-sent emails takes time, money, legal involvement. The Abnormal report estimates ~400 hours per year on average spent handling false alerts and incident remediation. (Abnormal AI)
- Compliance/ audit risk: Mis-sent sensitive data may trigger breach reporting obligations, audits, and stricter regulatory oversight.
- Loss of trust / competitive disadvantage: Clients may move to other providers if they believe their data is not safe; in regulated industries this can be critical.
What Organisations Can Do: Mitigation Strategies
Given the centrality of human error in email security risk, here are recommended actions:
1. Visibility & Monitoring of Outbound Email
- Implement tools and dashboards that monitor outbound email flows (not just inbound).
- Use real-time alerts for high-risk behaviours: e.g., email to large external distribution, new recipient domains, attachments of sensitive files. For example the Egress data used “real-time DLP prompts” detecting wrong recipient/attachment. (iaapuk.org)
- Supplement static rules with behaviour-based detection (i.e., deviating from typical patterns: unusual recipients, unusual file types, atypical sending volume).
2. Behavioural & Human-Centric Controls
- Adopt “human risk management” practices: identify staff with higher risk (frequency of mistakes, high volume of external communication) and provide targeted training/monitoring.
- Use simulation & training: phishing tests, mis-send training, “stop-and-think” prompts. Research shows continuous training reduces susceptibility. (arXiv)
- Build a culture of “pause before send” especially when attachments or external recipients are involved.
3. Technology Enhancements
- Deploy Data Loss Prevention (DLP) solutions that cover outbound data flows and integrate with email systems (M365, Google Workspace) plus enforce encryption when required.
- Use Behavioural AI / anomaly detection platforms: e.g., Abnormal AI emphasises modelling human behaviour rather than only rule-based filters. (Abnormal AI)
- Use email authentication and routing controls (SPF, DKIM, DMARC) to reduce spoofing/risk of malicious inbound emails, which reduce the cognitive load and “noise” that contributes to human error. (Though this addresses inbound risk more than mis-addressed outbound).
- Consider “send delay” workflows (e.g., hold outgoing emails for X minutes if large attachment/external recipient) to allow cancellation of mis-sent mail.
4. Process & Governance
- Define and enforce policies for handling sensitive data: classification, encryption, sharing.
- Enforce recipient verification controls (for example, re-confirm external recipient addresses when sending certain types of data).
- Audit trails & incident tracking: log outbound email incidents, near-misses, to feed into training and policy refinement.
- Board-level oversight: As many CISOs report (74%) that human error is top risk, the board must be informed and engaged. (securityinfowatch.com)
5. Metrics & Continuous Improvement
- Track metrics such as: number of misdirected email incidents/year, time to detect a mis-send, remediation cost, number of false positive alerts, number of DLP alerts.
- Use the data to refine controls, adjust training, detect high-risk users or workflows.
- Segment by user-type/role: high-volume external communicators (sales, legal, finance) often carry higher risk.
Key Takeaways
- Human error is not just a “soft” risk — it’s a leading driver of email-related security incidents in enterprise environments.
- Email remains a dominant vector (for both inbound threats and outbound mistakes), yet many organisations focus more on inbound threats.
- Outbound mis-addressing, incorrect attachments, and mis-sending sensitive information are major risks with real-world consequences (breaches, fines, lost trust).
- Technology alone won’t suffice; a combination of behaviour-based detection, culture/training, process controls and governance is needed.
- Organisations that treat human error as a top-tier risk (as many CISOs now do) will be better positioned to reduce incidents and mitigate damage.
- Here are three detailed case studies illustrating how human error is a leading risk factor in enterprise email security, followed by commentary and lessons learned from each.
Case Study 1: Misdirected Emails in Enterprises — Abnormal AI Survey (2025)
Overview & key findings
- Abnormal AI’s “2025 State of Misdirected Email Prevention” report surveyed over 300 security and IT professionals. (FinancialContent)
- 98 % of respondents said that a misdirected email (sending a legitimate message to the wrong recipient) is a significant risk, ranking higher than many forms of malware or credential‑theft threats. (FinancialContent)
- 96 % of organizations reported experiencing data loss or exposure from misdirected email in the past year. (Abnormal AI)
- 47 % of security/IT professionals only found out about the misdirected email because a recipient flagged it – not from a security system. (Abnormal AI)
- The study further notes that misdirected emails accounted for 27 % of all GDPR data‑protection incidents last year, contributing to over US$1.2 billion in fines worldwide. (FinancialContent)
Why this case matters
- It highlights that the risk is not just from external attacks (phishing, malware) but from internal mistakes.
- The fact that nearly half of the incidents are discovered by recipients instead of tools points to a visibility gap.
- The exposure and regulatory cost figures show that human‑error email events are material to business risk, not just an IT nuisance.
Lessons learned
- Enterprises often bias security investment toward inbound threats; outbound email errors (to wrong recipients) get less focus.
- Visibility & detection for mis‑sent emails need improvement (tools + process).
- Human‑centric controls (training, “pause & review” workflows) are critical.
- Regulatory risk (GDPR, fines) means these errors have real‑world business impact, not just “oops” moments.
Case Study 2: UK Regulatory Reporting — Information Commissioner’s Office / Egress Systems Findings
Overview & key findings
- The ICO’s “Security Trends” reports show that for Q1 2020/21, mis‑directed emails (data emailed to wrong recipient, sent to wrong person, failure to BCC) were the top cause of reported incidents — ahead of phishing. (egress.com)
- One note from Egress: “human error is the greatest risk … such as accidentally mis‑directing an email to the wrong recipient or attaching the wrong file.” (cyberlogic.co.za)
- According to a CISO strategy‑guide: 48 % of organizations had employees leave as direct result of outbound email security incident (27 % dismissed, 21 % voluntary). (Pub Media Box Storage)
Why this case matters
- It underscores that regulatory reporting backs up the human‐error risk: the “non‑cyber” incidents (i.e., not external attacker) still dominate.
- The fact that attachment errors and wrong recipients are leading causes of data‑loss shows this is a practical operations risk.
- The consequence for employees (dismissal, turnover) shows the human‑error risk affects personnel, not just systems.
Lessons learned
- Compliance teams need to treat mis‑sent emails as full‑blown incident types — tracking, reviewing, remediating.
- Policies around “outbound email” must be strengthened (recipient verification, attachments, BCC practices).
- Employee culture, fatigue, workload are factors – not just tools.
- Incident‑response must include “near‐miss” tracking (not only external attacks).
Case Study 3: Email Breach Metrics — Mimecast Limited / General Human Error in Data Breaches
Overview & key findings
- According to Mimecast’s “State of Human Risk” report: 95 % of data breaches in 2024 involved human error (negligent or unintentional employee actions). (SC Media)
- The same report identifies email security challenges as expected by 95 % of respondents in 2025. (SC Media)
- In another study, the Kiteworks Data Security & Compliance Risk Annual Survey noted email is still 16% more vulnerable than secure transfer protocols, and human error drives ~60 % of email‑related breaches. (FutureCISO)
Why this case matters
- It shows how pervasive human error is across all forms of data breach, not just targeted ones.
- It shows email remains a major vector — older technology, heavy use, many touch‑points.
- It shows that even organisations with mature security recognise human error as a top risk; it’s not “some small business problem”.
Lessons learned
- Training, culture, human‑factors engineering (e.g., reducing fatigue, distraction) are security levers.
- Email may need additional protective layers: real‑time recipients checks, content/context analysis, “second glance” workflows.
- When designing security control, assume “people will make mistakes” — design for error‑recovery, not just prevention.
- Metrics matter: track human‑related incidents (error, mis‑send, wrong attachment) as key risk indicators.
Commentary & Additional Observations
- The term “human error” may under‑state the complexity: it’s rarely “someone pressed wrong key” alone. Often underlying factors: fatigue, distraction, remote/hybrid working, complex tools, ambiguous interfaces, UI auto‑complete errors, high volume of communications. For example:
“43 % of respondents say fatigue is a top reason for mis‑directed email, 41 % say distraction.” (itbusinessnet.com)
- There is a visibility gap: many incidents are noticed by recipients, not by security teams or tools. This suggests the control set for outbound email is weaker.
- Traditional DLP or email‑filtering controls tend to focus on inbound threats and known malicious patterns. They struggle with “legitimate email, wrong recipient” type incidents. The Abnormal AI report emphasises this. (Abnormal AI)
- The value of behavioural / AI‑driven email monitoring is growing: modelling typical recipient patterns, attachment behaviours, unusual recipients etc. The Abnormal AI report points to this as a major control shift. (innovationopenlab.com)
- Human error in email security is a business risk not just technical: it links to regulatory fines, reputational damage, customer churn, employee loss (turnover/dismissal).
- Control design needs to balance: too many alerts / false positives decrease usability; punitive culture may discourage error reporting (which delays detection). The CISO guide notes disciplinary outcomes and employee turnover tied to outbound email incidents. (Pub Media Box Storage)
Key Takeaways for Enterprises
- Prioritise outbound email risk: Make “sending to wrong recipient/sending wrong attachment” a checkbox risk category in your security programme.
- Enhance visibility: Use tools that monitor outbound flows, pattern deviation, attachment anomalies. Don’t rely solely on manual detection or user + recipient‑reports.
- Design for human‑factor error:
- Introduce “pause & review” workflows for high‑risk emails (large attachments, external recipients).
- Simplify UI where possible, reduce cognitive load (auto‑suggest recipient verification, show big alerts if recipient is new or external).
- Protect against fatigue and distraction: policies around off‑hours, overload, remote/hybrid workflows.
- Train & empower staff: Move beyond basic phishing quizzes. Use scenario‑based training around mis‑send errors, attachment mistakes, external‑recipient verification.
- Track metrics: Monitor number of mis‑sent emails, time to detect, remediation cost, number of near‑miss alerts, employee turnover due to email incident.
- Governance & culture: Encourage “owning mistakes” rather than hiding them. Ensure reporting culture, not punitive only.
- Layer controls: Combine DLP, behavioural analytics, recipient‑verification prompts, content inspection. Traditional rule‑based tools alone are insufficient.
- Business alignment & risk view: Recognise that email mistakes are not purely IT issues — they are operational, legal, reputational. Board/senior leadership should be aware.