How can teams decide when to verify a payment request outside email?

Why This Matters for Security Teams

Payment verification outside email is a control decision, not a courtesy step. Email is easy to spoof, replay, forward, and socially engineer, so relying on the inbox alone creates a single point of failure for wire fraud, payroll diversion, and supplier impersonation. Current guidance from NIST SP 800-207 Zero Trust Architecture supports verifying trust at the moment of action, not at the moment of message receipt. That logic is reinforced by incident patterns seen in the DeepSeek breach, where exposed credentials and sensitive records demonstrated how quickly attackers exploit weak trust assumptions.

The practical issue is that many payment fraud attempts do not look malicious in the inbox. They arrive as routine invoices, urgent exceptions, or executive requests with just enough legitimacy to bypass normal habits. Security teams often over-index on sender recognition and under-index on transaction context, which leaves business email compromise able to route around controls that were designed for malware, not deception. In practice, many security teams encounter fraud only after funds have already moved, rather than through intentional verification discipline.

How It Works in Practice

The strongest decision rule is to verify outside email whenever a request changes money, bank details, payroll instructions, or identity details tied to payment authority. The second channel should be one that is harder to spoof and easier to audit, such as a known phone number from the vendor master record, a callback to a pre-established internal contact, or an authenticated workflow in a payments platform. Email should only be treated as a notification layer, not as proof.

Security and finance teams usually get better results when they define a small set of triggers and make them mandatory. Common triggers include:

• New or changed bank account details
• First-time payment requests from a sender
• Unusual urgency, secrecy, or pressure to bypass approval
• Requests that deviate from normal invoice format, amount, or recipient
• Payroll, executive, legal, or M&A-related payment changes

For higher-risk workflows, the verification step should require two-person review or a callback using independently sourced contact data. The control is stronger when the team documents what counts as “outside email” and what evidence is sufficient to proceed. That documentation matters because attackers often combine social engineering with stolen credentials, as seen in the JetBrains GitHub plugin token exposure, where trust in a familiar channel did not mean trust in the content. These controls tend to break down when invoice approvals are dispersed across chat, email, and ERP exceptions because no single owner can enforce the callback rule consistently.

Common Variations and Edge Cases

Tighter verification often increases friction, so organisations need to balance fraud resistance against payment speed and vendor experience. That tradeoff is especially visible in low-value, high-volume environments, where too many mandatory callbacks can create workarounds and “approval fatigue.” Best practice is evolving, but current guidance suggests using risk-based thresholds rather than a one-size-fits-all rule.

One useful variation is to exempt recurring payments only when the vendor record, bank account, approval chain, and amount pattern are unchanged. Even then, a surprise request should trigger re-verification. Another edge case is executive assistance or delegated authority: the closer the request is to leadership, the more likely it is to be socially engineered, so identity confirmation should be stronger, not weaker. Teams should also beware of “urgent” corrections sent from compromised but legitimate accounts, since the real risk is not just spoofing but takeover of a trusted sender. In those cases, a second channel is not optional because the email thread itself may be part of the attack.

Related resources from NHI Mgmt Group

• Who should verify payment changes when a trusted email request looks legitimate?
• How do teams decide whether ERP-depth SoD is worth the complexity?
• How should security teams decide whether to keep a legacy SEG with Microsoft 365?
• What should teams do when a posture score and an outside-in scan disagree?