When the email encryption option is activated on your email addresses at Microsoft, you will be able to benefit from the email encryption option when you send emails from your outlook or from webmail.
It is possible to make sure that the emails sent are automatically encrypted.
Outlook
In the "Option" menu you have the "Encrypt" menu which allows you to apply the encryption:
Select the desired encryption option
By clicking on the padlock you will automatically apply the encryption with the "Encrypt only" option
The option "Do not transfer" allows you to prevent the transfer of the mail, the impossibility for the recipient to make screen prints of the mail.