Try this first
- 1Exchange admin center > Mail flow > Rules > New rule.
- 2Condition: 'Sender is located' > 'Outside the organization'. Action: 'Apply a disclaimer' > 'Prepend' with an HTML banner. Fill in 'EXTERNAL: this mail comes from outside, verify the sender'.
- 3Add exceptions for partner domains you mail with a lot, otherwise every customer mail gets the banner and the signal is lost.
- 4Test by sending a mail from your personal Gmail to your work mail. Banner visible?
- 5Communicate to colleagues: 'if you see this banner on something that looks like a colleague mail, do not click'.
When to bring us in
Mailflow rule not behaving as expected or only visible in some clients? We can review the Exchange Online side and set it up cleanly.
See also
- I think I clicked a phishing linkNo shame, happens to everyone. The next fifteen minutes matter.
- A colleague's account is acting strangelySending mail in their name, rules hiding folders, unusual sign-ins. Suspicious.
- Lost the MFA app: new phone, no backup codesClassic problem after a phone upgrade. You are not the first to be locked out.
None of the above fits?
Describe your situation below. We pass your input plus the steps you already saw to our AI and return tailored next-step advice. If it's too risky to DIY, we'll say so.
Or skip the DIY entirely
Our Managed IT clients do not look these things up. One point of contact, a fixed monthly price, resolved within working hours.