In Confluence automation, the smart value user.emailAddress can be retrieved if the rule's actor can see their email address in Confluence UI.
This depends on the user's email visibility.

• https://id.atlassian.com/manage-profile/profile-and-visibility
  

 It would be better if this smart value can be retrieved regardless user's email address visibility.
For the case when assigning the unassigned guest user to space, and want to control space by guest user's email address, the rule does not work if the actor can not see the guest user's email address.