Sending sensitive documents to clients with encrypted email

How to send confidential documents to clients by encrypted email in Outlook, so only the intended recipient can open them.

Send an encrypted email

1. Start a new email and add the recipient.
2. Turn on encryption:
   • New Outlook / Outlook on the web: Options → Encrypt, then choose Encrypt.
   • Classic Outlook: Options → Encrypt (padlock), then choose Encrypt-Only.
3. Check for the banner at the top of the message confirming it's encrypted, then send.

Attaching files

Attach the file as an actual copy, not a OneDrive/SharePoint link. Encryption doesn't work with cloud links, which is why it can look like you can't attach anything.

• Use Attach → Browse this computer.
• If Outlook asks, pick Attach as copy, not Share link.

What the client sees

• Clients on Outlook or Microsoft 365: the message usually opens as normal.
• Everyone else (Gmail, Yahoo, etc.): they get an email with a Read the message button, then sign in with their Google or Microsoft account or request a one-time code. They can reply securely from there, and replies stay encrypted.

Encrypt vs. Do Not Forward

Use Encrypt for client documents. Do Not Forward also stops the client from forwarding or passing the document on, for example to their accountant, so only use it when that's what you want.

If you don't see the Encrypt option, or the recipient can't open the message, submit a ticket to IT.