When you need to protect the confidentiality of an email, you can encrypt it. Encrypting an email means that it is converted from plain readable text to encrypted text that can only be read by the intended recipient.

Outlook currently supports two encryption options:

S/MIME encryption - To use this encryption, the sender and recipient must have an email program that supports this standard. Outlook supports i.a. The S/MIME standard.

Office 365 Message Encryption (OME) - If you want to use message encryption directly in Microsoft 365, it is included in e.g. the Business Premium and Office 365 Enterprise E3 licenses or with a separate add-on.

The former S/MIME encryption requires the recipient to have at least the same level of security as yourself, while Microsoft 365 message encryption can be received by anyone. If you need to be sure that the recipient gets your encrypted email, it can be quickly implemented with the right Microsoft 365 license.