Business Email Compromise: What Small Businesses Should Check First
If a business email account is misused, customers, suppliers and staff can be tricked into paying fake invoices or trusting false instructions.
Quick answer: stop and verify using a trusted contact method before you pay, approve, reply or ignore warning signs.
Quick answer
If a business email account may be compromised, secure the account from a trusted device, review sign-ins and forwarding rules, protect it with MFA, and independently warn affected staff, customers or suppliers where needed.
Fast decision
What this means for a small business
If a business email account is misused, customers, suppliers and staff can be tricked into paying fake invoices or trusting false instructions.
Most business cyber problems become expensive when a normal-looking request is handled too quickly. A safer process gives staff permission to pause, check the source, and ask for help before money, access or sensitive information is exposed.
This guide uses fake examples only. It is designed to help you prepare a safer next step, not to collect private records or replace professional investigation.
Warning signs to check
- Unexpected sent emails or replies customers mention but staff do not recognise.
- New inbox rules, forwarding rules or deleted-message behaviour.
- Staff receive login prompts or password reset notices they did not start.
- Customers or suppliers report changed bank details or unusual instructions.
What to do now
- Change passwords only from a trusted device and protect the account with two-step login.
- Check forwarding rules, mailbox rules, delegates and recent sign-in activity.
- Warn affected staff, customers or suppliers using a known contact path.
- For money already sent, contact the bank immediately.
What not to do
- Do not rely on the suspicious email thread to confirm instructions.
- Do not delete evidence before taking screenshots or saving details.
- Do not ask staff to share passwords, codes or full customer records.
Related Business Cyber Safety links
What to do if business email is hacked
Continue with the related Business Cyber Safety guide.
Fake invoice scam warning signs
Continue with the related Business Cyber Safety guide.
Scam Safety hub
Use this when the issue looks like a scam message, fake invoice or payment redirection attempt.
Essential Eight small business hub
Review broader basics like two-step login, backups, updates, admin access and safer devices.
Benefits and practical outcomes
Use these outcomes as a practical check on whether the advice is making the situation clearer and easier to manage.
Reduce avoidable exposure
Simple account, update, access and verification controls can reduce common preventable weaknesses.
Recover with less guesswork
Documented owners, backups and evidence make incident response and restoration easier to organise.
Give staff a repeatable check
Plain-English steps are easier to follow than relying on memory when an unusual request arrives.
Prioritise the next fix
A short checklist helps separate urgent controls from improvements that can be scheduled later.
Example: an email account triggers an unusual sign-in
A staff member receives an unexpected sign-in alert. The business uses a trusted device to review recent sign-ins, changes the password where needed, checks MFA and recovery methods, and reviews forwarding rules.
Outcome: the account is checked systematically instead of relying on the suspicious email thread.
FAQ
Is this a formal cyber audit?
No. This is a practical self-check guide, not a formal audit, investigation, certification or guarantee.
Should I share passwords or login codes?
No. Do not share passwords, login codes, banking passwords, card numbers or private customer records through this guide.
What if money has already been sent?
Contact your bank immediately. Then collect the invoice, email details and verification notes for review.