What to Do If Your Business Email Might Be Hacked
When business email may be hacked, the first aim is to secure access, preserve evidence and warn people who could be affected.
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
When business email may be hacked, the first aim is to secure access, preserve evidence and warn people who could be affected.
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
- Customers or suppliers received strange emails from your business.
- Staff cannot find expected emails or notice deleted messages.
- There are unknown inbox rules or forwarding rules.
- Someone approved a login prompt they did not expect.
What to do now
- Secure the account and review recovery details.
- Check sent mail, rules, forwarding and delegates.
- Warn customers or suppliers if they may receive fake payment instructions.
- Review whether any payments or sensitive records were affected.
What not to do
- Do not announce that everything is safe until the account has been reviewed.
- Do not keep using the same device if you suspect malware.
- Do not enter passwords through links in warning emails.
Related Business Cyber Safety links
Microsoft 365 warning signs
Continue with the related Business Cyber Safety guide.
Business email compromise
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.