Katmai Government Services

How do I send an encrypted email message?

To send a message with encryption, choose one of the two options available under the Encrypt button: Encrypt or Encrypt and Prevent Forwarding.

Are attachments also encrypted?

All attachments are encrypted. Recipients who access the encrypted email via the Office Message Encryption portal can view attachments in the browser.

Attachments behave differently after they’re downloaded depending on the encryption option used:

• If you choose the Encrypt option, recipients with Outlook.com and Microsoft 365 accounts can download attachments without encryption from Outlook.com, the Outlook mobile app, or the Mail app in Windows 10. Other email accounts using a different email client can use a temporary passcode to download the attachments from the Microsoft 365 Message Encryption portal.

• If you choose the Encrypt and Prevent Forwarding option, there are two possibilities:

  • Microsoft Office attachments such as Word, Excel or PowerPoint files remain encrypted even after they’re downloaded. This means that if the recipient downloads the attachment and sends it to someone else, the person they forwarded it to won’t be able to open the attachment because they don’t have permission to open it.

    Note that if the recipient of the file is using an Outlook.com account, they can open encrypted Office attachments on the Office apps for Windows. If the recipient of the file is using an Microsoft 365 account, they can open the file in Office apps across platforms.

  • All other attachments, such as PDF files or image files, can be downloaded without encryption.