A message encrypted by Office 365 Message Encryption is delivered to a recipient’s inbox like any other email. It contains an HTML file attachment that the recipient can open to view the message on the Office 365 Message Encryption portal. The recipient can choose to either sign in with a Microsoft account or a work account associated with Office 365, or use a one-time passcode to view the message.
You can read a message without signing in by requesting and entering a one-time passcode (OTP).
To read an encrypted message by using OTP
Follow the instructions in the email message to save the attachment.
Open the message.html file in the email.
Select Don’t want to sign in? Get a one-time passcode to view the message.
Tip: You can also request a one-time passcode in the portal when you are asked to create a Microsoft account to read encrypted messages.
The passcode is sent to you in an email message. Get the passcode, enter it, and then click CONTINUE.
You can now view your message.
Tip: Each passcode expires after 15 minutes. If that happens, or if you can’t open the message for any reason, start over by opening the attachment again and following the steps. Make sure the reference code in the email containing the passcode matches the reference code in the portal.