Email encryption protocols question

Hey all. Studying up on the CISSP and going through secure email protocols. As I understand it SMTP is clear text, hence the need to encrypt emails when needed. I'm reading up [on this article](https://learn.microsoft.com/en-us/microsoft-365/compliance/email-encryption?view=o365-worldwide) about how Microsoft handles email encryption options, they state:

>Microsoft 365 uses encryption in two ways: in the service, and as a customer control. In the service, encryption is used in Microsoft 365 by default; you don't have to configure anything. For example, Microsoft 365 …

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