Encrypting an email disguises it's contents so that only the intended recipient can access and read them. Email can be a vulnerable medium, especially when sent over an insecure or public network because it can be intercepted in transit by other users. Encryption makes the contents unreadable to anyone other than the recipient so that even if the message is intercepted, they won't be able to read it. Email attachments are also encrypted when using email encryption.
The standard layer of protection Microsoft 365 offers is called Transport Layer Security (TSL) this type of encryption protects the connection and not the message, so when we have the valid need to send sensitive information by email it's worth while adding an extra layer of security.
How to Encrypt an email
1. Open a New Message
2. Click onto the Options Tab
3. Click Encrypt
4. Choose Encrypt from the list of options