Overview
You can create one or multiple Schedule Day Event mail messages that can trigger off of X days before / after a set amount of occurrences. This could be used to send different reminders for events coming up or to remind users that a course is about to expire.
Creating the Email Message
Login to the Administrative side of your database, and navigate to Settings --> Assignments --> Email Messages. Click the Add New Email button. Input a Title, choose the type Triggered Schedule Day Event, and click the "Save" button.

Enter a title, subject, and then start adding your desired operators. Select an operator from the list seen on the right hand side, this will add them to the body of the email. After you've finished composing your email message, select the "Save" button.

Creating the Triggered Email
Navigate to Settings --> Assignments --> Triggered Emails. Select the "Add New Triggered Email" button.
Navigate to Settings --> Assignments --> Triggered Emails. Select the "Add New Triggered Email" button.

Main Fields
Input a Title, choose the Type, and choose the date range for the Triggered Email.Schedule Day Event Fields
The trigger is fired off the number of days before or after an occurrence (The occurrence is a single day event, seen on the calendar of a product)Select the + Add Mail Message button to set how the email message is triggered

Select a message, enter X days, select before/after and enter X amount of occurrences, then select the Save button
Options
You can add more than one mail message by simple selecting the + Add Mail Message again and repeating your steps(Example)

Assigning to a Product
This trigger needs to be assigned, one option is to assign it to a product.Search for your product, Select Assignments, Select Emails, Select Triggered Emails, Select and drag the desired trigger over to the assigned section, And then Save

For more information on assigning items, see the Product Assignment Video, or the Categories and Regions help files.