With the userFilter element, you determine who should be notified when there is a new training available. The filter consists of a filter type and its value.

You can define the target users based on one or more of the following criteria:

User group

The filter type USER_GROUP looks at the user group people belong to. 
Example: You create the "training group" user group and add all the people who should receive training to this group.

"userFilter":
    {"type": "USER_GROUP", "value": "training group"}

User email address

The filter type USER_EMAIL_DOMAIN looks at the domain name of the email address associated with a user's Confluence account.
Example: Only people from Radbee should receive training on particular pages, so you only want people whose email address end in "@radbee.com".

"userFilter":
    {"type": "USER_EMAIL_DOMAIN", "value": "radbee.com"}