Certification Aid wants to include SSJS in an email message.

To include Server-Side JavaScript (SSJS) in an email message, you need to use the : This is a valid way to include SSJS in an email. It specifies that the enclosed code should be executed on the server.

Salesforce SSJS Documentation

: This is another valid syntax. It specifies that the code within the script tag is JavaScript and should run on the server.