An urgent invoice sent by a known supplier, a transfer request signed by management or a Microsoft 365 alert may seem ordinary. That is precisely what makes these messages dangerous. Knowing how to detect fraudulent email helps prevent a simple click from becoming account compromise, financial fraud or operational disruption.
For a business, email remains one of the main entry points for attackers. Modern campaigns no longer rely solely on obvious spelling mistakes or generic messages. They exploit social networks, supplier relationships, payroll periods, ongoing projects and collaborative tools used daily. Vigilance must therefore become an operational reflex, supported by reliable technical controls.
Why fraudulent emails are so convincing
Phishing aims to obtain quick action: open an attachment, click a link, transmit a password, modify banking details or approve a payment. The attacker rarely seeks to force a complex system when they can convince an authorized person to open the door for them.
In CEO fraud and business email compromise scenarios, the message may contain no malicious file. It may simply ask a finance team member to process a confidential payment or a human resources person to share a document. The risk is therefore not limited to suspicious links: it also concerns unusual requests that bypass normal validation processes.
Artificial intelligence tools have also improved the writing quality of fraud attempts. A message can be clear, personalized and written in impeccable English. The presence or absence of errors is no longer a sufficient criterion for judging its legitimacy.
How to detect fraudulent email: signals to examine
A single clue does not always prove that a message is malicious. However, several anomalies combined justify immediate stoppage and independent verification. The right reflex is to slow down before acting, especially when an email creates a sense of urgency or involves money, access or sensitive data.
Verify the sender's true identity
The name displayed in the inbox is not enough. Fraudsters can use the name of a leader, partner or known department. Examine the full address and, most importantly, the domain name after the @ symbol.
An address like billing@supplier-support.com can imitate a supplier whose official domain is supplier.com. Variations are sometimes very subtle: a letter replaced, a hyphen added, a nearby domain or a different extension. On mobile, the full address is often hidden by default. Encourage employees to display it before responding or clicking.
Also be wary of messages from an internal address requesting unusual action. A compromised Microsoft 365 mailbox allows an attacker to write from an authentic account, with the actual history of exchanges. In this case, the context of the request becomes more revealing than the address itself.
Spot urgency, secrecy and procedural breakdown
Fraudulent emails seek to reduce thinking time. They mention an imminent deadline, account suspension, outstanding invoice, confidential request from management or an opportunity to seize without delay. This pressure is a major signal, especially if it requires bypassing a usual approval.
A request to change a bank account, purchase gift cards, transfer funds or share data must always follow an established process. Even if the email seems to come from a known person, confirm the request through a separate channel: call the number already registered in your files, open a new Teams conversation or verify directly with the supplier. Do not use the phone number or link provided in the suspicious message.
Caution may add a few minutes to processing a legitimate request. It is a reasonable trade-off compared to the cost of diverted payment or data breach.
Inspect links and attachments without opening them
A link can display the name of a known service while directing to a fake login portal. On a computer, hover over the link to see the destination address. On mobile, press and hold the link when the application allows. Look for imprecise domains, incoherent character strings, subtle misspellings or addresses that do not match the advertised service.
Attackers frequently use fake document sharing notices, full mailbox alerts, delivery receipts or invoices. If you are actually expecting a document, access the relevant service from your browser or usual application instead. Do not go through the email button.
Attachments require the same caution. ZIP, HTML, ISO, EXE files and Office documents requesting macro activation require heightened attention. A PDF is not automatically safe either: it can contain a link to a fraudulent site. A reassuring filename is never proof.
Look for context inconsistencies
A message may seem technically credible but not match the situation. Why is this supplier writing to you? Why is the finance department asking for an HR document? Why is your manager contacting you from a personal address for an unusual operation?
Compare the tone, timing and content with previous exchanges. An existing conversation can be hijacked after compromise of a partner account. A message inserted into a real discussion thread therefore deserves as much caution as a new email, especially when it introduces a new attachment, new banking details or a request for access.
Do not confuse authentication with legitimacy
Some organizations use domain authentication mechanisms to reduce identity spoofing. These protections are essential, but they do not guarantee that a message is safe. An email sent from a compromised supplier account may pass technical controls while being fraudulent.
The question to ask remains simple: is this request consistent with the person, the business relationship and the intended procedure? Technologies filter much of the threat. They do not replace human judgment on a sensitive request.
What to do when a message seems suspicious
Do not reply, do not forward the message to colleagues and do not click on anything to get more information. Report it to your IT team or cybersecurity provider according to internal process. If your email platform offers a phishing reporting function, use it: it helps the security team analyze the message and protect other recipients.
If you have already entered a password on a questionable site, act immediately. Change this password from a secure device, notify the responsible team and check active connections, forwarding rules and unusual activities in your account. When multi-factor authentication is in place, it can prevent complete takeover, but it should not delay reporting.
If an attachment has been opened or a payment has been made, time becomes critical. The IT team, finance and, if necessary, the financial institution must intervene quickly to limit spread, preserve evidence and attempt to block the transaction. Immediate transparency protects the company more than an incident hidden for fear of making a mistake.
Build a defense that does not rely solely on employees
Training teams is essential, but asking each person to identify every threat alone is not a sufficient strategy. Effective defense combines advanced email filters, endpoint protection, multi-factor authentication, appropriate access policies and monitoring capable of detecting abnormal behavior.
Email rules must in particular limit domain spoofing, analyze URLs and attachments, then block or isolate at-risk messages. Endpoint protection adds an essential layer when a malicious file bypasses the filter. Finally, continuous monitoring allows you to identify a compromised account before it is used to spread new fraud internally or to your partners.
Phishing simulations and short training have their place when linked to real organizational scenarios: payment requests, document sharing, license renewal, strategic suppliers or cloud tools. The goal is not to trap employees. It is to strengthen their ability to interrupt a risky action and report it without hesitation.
For companies that do not have a complete internal security team, a proactive defense partner like SentriCorp can structure these layers of protection, monitor warning signals and support response when doubt arises. Your security does not depend on a single tool or a single careful click: it rests on a collective ability to verify, report and intervene before fraud reaches your operations.