As part of Microsoft’s message protection efforts, Microsoft has evolved its email encryption solutions to provide a unified sender experience whether you're sending a protected message inside of your organization or outside your organization
With the latest updates to Microsoft 365, Microsoft now provides users with the same experience securing messages both inside and outside the organization. In short, the sender doesn't have to worry about choosing the right encryption method for each recipient.
Recipients will see improvements as well. Regardless of the recipient's email provider or email application, they'll be able to read the encrypted message. If the recipients use Outlook, the experience is seamless. They'll receive the message, see that it's encrypted, and be able to open and read the message. If they can't use Outlook, they'll receive a limited-time web-view link that will let them read the message. There's no software to install. Simply open the web-view link to see the encrypted message.
Protected messages allow the sender to set specific permissions on a message, such as Do Not Forward or Do Not Print. If you receive a protected email message sent to your Microsoft 365 account in Outlook 2016 or Outlook on the web, the message should open like any other message. You'll see a banner at the top of the message that informs you of any restrictions on the message.
If you're using a different email account or email program, you may receive a notification that you've received a protected message and need to take additional action.
If you're using a Microsoft 365 email account in Outlook 2016 or Outlook on the web, you shouldn't have to do anything special to read your message.
If you have a Microsoft 365 account and you're using the Outlook mobile app, the message should just open.
Some email clients and services can't automatically open protected messages. If you have an email account with Yahoo or another Internet Service Provider, you'll need to obtain a single-use code to read the message.