Essential Checklist: How to Identify a Suspicious Email Message Before It’s Too Late

Author:

 

 Essential Checklist: How to Spot a Suspicious Email

Below are the key elements to evaluate before clicking on links, opening attachments, or replying.

# Checkpoint What to ask / look for Why it matters
1 Sender & “From” address • Does the sender’s email domain match what you expect (e.g., @yourcompany.com, @your‑bank.com)? • Is the display name masking a different domain (e.g., “Bank Support” but @gmail.com or misspelt domain)? • Is it the first time you’ve received mail from this sender? (Microsoft Support) Attackers often spoof or hijack display names, but the full email address still reveals anomalies.
2 Misspelt / altered domains • Is the domain slightly misspelt (e.g., amaz0n.com vs amazon.com)? • Are there added words/numbers to the domain (e.g., bank‑login.com instead of bank.com)? (itgovernance.co.uk) Subtle domain modifications are a frequent trick to deceive recipients.
3 Urgent language / pressure • Does the email demand immediate action (“Act now!”, “Last chance”, “Your account will be closed”) • Does it threaten negative outcomes if you don’t act quickly? (bitlyft.com) Urgency is used to push recipients into acting before they scrutinise the message.
4 Unexpected links or attachments • Are there links where the displayed text doesn’t match the destination when you hover over it? • Is there an unexpected attachment (especially .zip, .exe, .scr, or unknown extension) you didn’t ask for? (Cofense) Malicious links/attachments are the main vector for malware, credential theft and phishing.
5 Requests for credentials / sensitive info • Is the email asking you to provide username/password, payment info, or confirm personal data via email or link? • Is it saying “We’ll reset your password if you click here”? (OCC.gov) Legitimate organisations rarely ask for credentials via email; this is a common phishing indicator.
6 Generic greetings / tone out of place • Does it say “Dear Customer” rather than using your name? • Is the style/tone inconsistent with what you normally receive from the sender? (Cofense) A message that feels “off” in tone or personalization is a sign of impersonation or mass‑mailing.
7 Spelling, grammar or style errors • Are there obvious mistakes, awkward phrasing or low‑quality layout/images? • Is the message poorly formatted compared with official communications? (Cofense) Professional organisations normally proof‑read emails; errors often signal a scam.
8 Too good to be true / unsolicited offers • Did you receive an email about winning a prize or getting large returns you didn’t expect? • Did you not initiate any contact but are being asked for something? (Ohio University) Offers that arrive out of the blue and seem unrealistic are typical scam patterns.
9 Mismatched “From” vs “Reply‑to” vs “Return‑Path” • Does the “reply‑to” address differ from the “from” address? • Is the return‑path or header unusual (for tech‑savvy users) indicating redirection? (arXiv) Email header anomalies often reveal deeper spoofing or redirection.
10 External sending / unexpected sender flag • Is the sender marked “[External]” or flagged outside your organisation? • Is the sender someone you know but the context is odd/unexpected? (Phishing Education & Training) Recognising external emails or unexpected communication helps reduce internal trust‑based mistakes.

 Context & Commentary

  • According to the Cybersecurity & Infrastructure Security Agency (CISA), messages using urgency, emotional appeals, suspicious links or unrecognised domains are hallmark phishing indicators. (CISA)
  • As noted by the National Cyber Security Centre (UK), while spelling and grammar remain useful cues, attackers are increasingly using flawless language (especially via AI), so other indicators must also be checked. (Microsoft Support)
  • Training and awareness matter: Research shows users often rely on irrelevant cues (like appearance or awards) rather than core red‑flags, meaning structured checklists are more effective. (arXiv)
  • Organisations such as Cofense list consistent indicators (links, sender domain, threats, attachments) across phishing campaigns, emphasising the importance of early detection. (Cofense)

 What to Do If You Identify a Suspicious Email

  • Do not click any links or open attachments until verified.
  • Verify sender via a trusted method (e.g., call known number, open website independently).
  • Report the email to your organisation’s IT/security team (or use the “Report Phish” button if available).
  • If you accidentally clicked/opened, notify IT immediately so they can isolate risk and check for breach.
  • Keep a log of the suspicious email (time, sender, subject) for follow‑up and audit.

 Key Takeaways

  • Most successful phishing attacks exploit human behaviour (urgency, trust, mistakes) — so your behaviour is as important as your technical defences.
  • Use the checklist as a habit — hovering over links, verifying senders, pausing before acting — those few seconds can prevent major breach.
  • Even though email filters and gateways help, your vigilance is essential: tech filters can’t catch every cleverly crafted message.
  • Organisations should embed this checklist into training and build a culture where reporting suspicious emails is encouraged (not shame‑based).
  • Always assume: if you’re unsure, pause and verify. It’s better to take the extra moment than proceed in error.

Here’s a detailed case-study and commentary overview on identifying suspicious emails, based on real incidents and best practices.

 Case Studies: Suspicious Email Detection

1. Business Email Compromise (BEC) – Fake CEO Request

  • Scenario: A mid-sized UK finance firm received an email appearing to come from the CEO, requesting an urgent wire transfer to a “vendor.”
  • Red flags identified:
    • Sender’s domain was slightly different: ceo-company.co.uk instead of company.co.uk.
    • Urgent language: “Transfer immediately, urgent client deadline.”
    • Unexpected request: finance team had no prior vendor communication.
  • Outcome:
    • The finance team verified via phone and discovered it was a phishing attempt.
    • No funds were transferred; incident reported to regulators.
  • Key takeaway: Always verify unusual requests, especially when they involve money, using an independent channel.

2. Malicious Attachment – HR Phishing

  • Scenario: Employees at a UK retail chain received an email claiming to be from HR about new holiday schedules, with a PDF attachment.
  • Red flags identified:
    • Generic greeting: “Dear Employee” rather than name.
    • Attachment file type suspicious: .exe disguised as .pdf.
    • Minor grammar errors: “Please find attached your schedul.”
  • Outcome:
    • The IT team flagged the attachment via sandbox analysis; malware detected and blocked.
  • Key takeaway: Always inspect attachments, especially unexpected ones, and verify with sender.

3. Impersonation & Fake Invoice – Small Business

  • Scenario: A UK SME received an invoice email from a supplier claiming overdue payment.
  • Red flags identified:
    • Email domain slightly misspelt (suppl1er.com instead of supplier.com).
    • The invoice amount was higher than normal.
    • Request to pay via a new bank account.
  • Outcome:
    • Payment was paused; supplier contacted through known official channels.
    • Confirmed fraud attempt; flagged in accounting system.
  • Key takeaway: Cross-check payment requests via pre-established contact methods; never rely solely on email content.

4. AI‑Generated Phishing Email – Sophisticated Scam

  • Scenario: Employees received emails with highly realistic tone, contextually accurate to the business, using AI-generated content.
  • Red flags identified:
    • Subtle mismatches in links vs display text.
    • Sender email slightly off but looked authentic.
    • Requests for credential confirmation, claiming “security update.”
  • Outcome:
    • Employees trained to hover over links and verify domain caught the scam.
    • IT enforced multi-factor authentication to block compromised credentials.
  • Key takeaway: AI phishing can be highly convincing; vigilance, MFA, and domain checks are critical.

 Commentary & Lessons Learned

  • Human behaviour is the key vulnerability: Attackers exploit urgency, authority, trust, and emotion. Training and structured checklists reduce errors.
  • Layered approach works best: Technical controls (spam filters, sandboxing, MFA) combined with user awareness provide stronger defense.
  • Verification over assumption: Any unusual request, link, or attachment should be independently verified before action.
  • Proactive culture: Organisations that implement phishing simulations and easy reporting see higher reporting rates and lower breach incidents.
  • Checklist adoption: Integrating the earlier “10-point suspicious email checklist” into daily workflow enhances detection and reduces risk.

 Best Practices Highlighted in Cases

  1. Hover over links to inspect actual URLs.
  2. Verify senders via independent communication channels.
  3. Treat urgent requests with caution, even from high-ranking executives.
  4. Scan attachments before opening; suspicious file types require IT inspection.
  5. Encourage a no-blame culture for reporting suspicious emails.
  6. Implement multi-factor authentication and strong password policies.
  7. Update technical defenses with domain authentication (SPF, DKIM, DMARC) and spam filters.

 

Categories: Digital Marketing, News