Email security gaps in financial services are now governance failures

At a glance

What this is: This whitepaper argues that email security gaps in financial services are now governance failures, not just tooling gaps, because human error and missed outbound incidents drive most of the risk.

Why it matters: It matters because IAM, PAM, and security teams must treat email as an identity and access governance problem, especially where third-party access, compliance exposure, and human error intersect.

By the numbers:

• Up to 68% of breaches in financial services stem from people making honest mistakes, according to Knowbe4.
• 90% of outbound email security incidents go undetected by traditional systems, according to Knowbe4.

Context

Financial services email risk is not just a content-filtering problem. It is a governance problem because the most common failures involve people, access, and control boundaries that traditional email security tools do not model well.

In this whitepaper, Knowbe4 frames the issue around human error, outbound detection gaps, and the pressure created by compliance obligations and third-party access. The identity angle is real: when email is used to move sensitive data, governance must cover who can send, share, and approve information, not just whether a message is malicious.

Key questions

Q: What breaks when email security is not aligned to human risk in financial services?

A: The main failure is that traditional filtering and malware detection do not stop legitimate users from making unsafe email decisions. That means misdirected financial data, policy violations, and phishing-driven mistakes can still create reportable incidents even when the inbox appears protected. Governance has to cover user action, not only message content.

Q: Why does outbound email create such a large governance gap for financial firms?

A: Outbound email is where accidental disclosure becomes business impact, but many controls are still tuned to inbound threats. If the organisation cannot detect sensitive data leaving the environment, it loses visibility into client-data exposure, regulatory breach risk, and downstream trust damage. That is why outbound monitoring belongs in the core control set.

Q: What are the signs that email governance is failing in an enterprise?

A: The clearest signs are excessive shared mailbox access, stale delegation rights, unexpected forwarding rules, weak review records and inconsistent handling of privileged inboxes. If those conditions exist, the organisation is likely relying on filtering tools to cover an access problem they cannot solve on their own.

Q: How should financial organisations govern third-party email access and collaboration?

A: They should treat external mailboxes, delegated inboxes, and shared communication channels as controlled access routes. That means defining ownership, enforcing lifecycle offboarding, and applying the same review discipline to third-party communication paths that they apply to other privileged access. Without that, collaboration becomes an unmanaged disclosure channel.

Technical breakdown

Why human error defeats email filtering

Email controls often focus on malware, phishing signatures, and domain reputation, but many financial services incidents begin with legitimate users making unsafe decisions. A misdirected attachment, a careless reply-all, or a rushed click can bypass technical controls because the message itself may look normal. That is why email security in this context is partly a human-risk problem and partly an identity-governance problem: the user is authenticated, but the action is still unsafe. Traditional tools are weak at spotting intent, context, and abnormal business process behaviour.

Practical implication: strengthen controls around risky actions, not only malicious content.

Outbound email and the hidden exfiltration gap

Outbound email is a common blind spot because many tools are tuned to block inbound threats rather than detect sensitive data leaving the organisation. In financial services, that matters because the loss event may be a single accidental disclosure rather than a classic attack. Once a message leaves the tenant, the organisation may have limited visibility into who received it, whether it was forwarded, or whether it violates policy. That makes email a data-governance channel as much as a communications channel.

Practical implication: monitor and govern outbound sharing as tightly as inbound threat traffic.

Third-party access expands the email trust boundary

As third-party access grows, email becomes a coordination layer for external parties who may not sit inside the same assurance model as employees. That widens the trust boundary and increases the chance that access, approvals, and data handling drift away from policy. In practice, the problem is not only mailbox security. It is lifecycle control over external identities, delegated communication rights, and the business process that allows sensitive information to move through email in the first place.

Practical implication: treat third-party email pathways as governed access routes, not informal collaboration.

Threat narrative

Attacker objective: The objective is to move sensitive financial data or exploit trusted email workflows in a way that produces regulatory, financial, or reputational damage.

1. Entry occurs when a legitimate user sends sensitive financial information to the wrong recipient or clicks a phishing link that appears business-relevant.
2. Credential or trust abuse follows when the message uses a valid mailbox, trusted relationship, or delegated access path that the email stack is unlikely to block.
3. Impact occurs when the incident becomes a data disclosure, fraud enablement, compliance breach, or loss of client trust that traditional outbound controls did not detect.

Breaches seen in the wild

• Zacks breach claim 2025: A hacker leaked 12 million Zacks accounts in 2025, claiming domain admin access in 2024; HIBP verified the data, Zacks has not confirmed.

Read and download The State of NHI & AI Agent Breach Report 2026, covering 200+ breaches impacting Non-Human Identities including AI Agents.

NHI Mgmt Group analysis

Email security in financial services is now a governance discipline, not a mail-filtering discipline. The article’s core point is that traditional controls miss the way modern email risk actually materialises: through human error, trusted communication paths, and policy gaps. That shifts the problem from threat blocking to control design across identity, access, and information handling. Practitioners should treat email governance as part of the security operating model, not as a separate IT nuisance.

Human error is the named failure mode, but the real control gap is unmanaged decision authority. People make the final call on recipients, attachments, and disclosures, yet most organisations still rely on controls built to detect malicious content rather than unsafe business decisions. That creates a verification trust gap in which legitimate users can still cause high-impact incidents. The practitioner lesson is to govern the action path, not just the message path.

Third-party access expands the email trust boundary in ways many compliance programmes under-model. When contractors, partners, and service providers participate in email-driven workflows, the organisation inherits their handling risk without always extending the same lifecycle controls. That intersects directly with IAM and identity governance because access rights, delegation, and offboarding become part of the email control problem. The practitioner response is to align external identity governance with email data-handling rules.

Outbound detection failure is the operational reason email becomes a financial-services control gap. If 90% of outbound incidents are missed by traditional systems, then visibility is failing where loss actually occurs, not where prevention is easiest. That means compliance teams need control evidence around leakage detection, user behaviour, and escalation paths, not just inbound threat blocks. Practitioners should measure the controls that catch accidental disclosure before it becomes reportable.

What this signals

Human-risk email governance: financial services teams should stop treating outbound email as a peripheral productivity issue and start measuring it as a control surface. The meaningful question is whether policy, identity, and escalation paths can stop a user mistake before it becomes a disclosure event.

A stronger programme will connect DLP, mailbox controls, and identity governance so that external sharing, delegated access, and policy exceptions are all visible in one risk view. Without that connection, email incidents remain visible only after the damage is done.

For practitioners

• Tighten controls on risky send actions Apply approval, warning, and review workflows to external forwarding, bulk sends, and messages containing regulated data so that unsafe decisions are interrupted before delivery.
• Monitor outbound disclosure paths Extend detection to outbound email, attachment sharing, and forwarding chains so the programme can see where sensitive information actually leaves the organisation.
• Map third-party mailbox access Inventory delegated inboxes, shared mailboxes, and external collaboration paths, then define who can approve, send, and retain sensitive communications.
• Build human-risk reporting for email incidents Track misdirected mail, policy overrides, suspicious clicks, and accidental disclosures as governance signals for compliance and risk teams, not just help desk noise.

Key takeaways

• Financial services email incidents often begin with ordinary user behaviour, which means prevention has to extend beyond filtering and malware detection.
• Outbound email is a governance blind spot when organisations cannot see sensitive data leaving the environment or distinguish unsafe disclosure from normal communication.
• The most effective response is to combine human-risk controls, identity governance, and outbound monitoring so that email handling is auditable before exposure turns into loss.

Key terms

• Outbound Email Monitoring: The practice of watching sending patterns, destinations, and forwarding behavior for signs that an account has been compromised or is behaving abnormally. It is valuable because misuse often shows up in outgoing mail before a broader incident is detected.
• Human Risk Management: The practice of managing how people interact with security controls, especially under pressure, distraction, or deception. It combines training, policy, and friction management so identity systems are still usable enough that users do not bypass them in day-to-day work.
• Delegated Mailbox Access: Delegated mailbox access is permission that allows one account or user to read, send, or manage another mailbox. It is useful for operations, but it increases blast radius if the delegate account is abused or the permission is never reviewed.
• Email Governance: Email governance is the set of policies and controls that define how mail systems are administered, monitored, and integrated with broader security oversight. It includes access, posture, logging, and third-party trust decisions, not just filtering and anti-phishing controls.

Deepen your knowledge

NHI Foundation Level course, the industry's only accredited NHI security programme, covers NHI governance, machine identity security, and secrets management alongside core identity controls. It helps security and identity practitioners connect access governance to the broader risk surface their programmes depend on.