Steps to Reproduce in Confluence:

1. Create a user, and set to 'Disabled'
2. Create a Group and make this user a member of this group
3. Share a page with the group
   This results in an email being sent to the inactive user

Steps to Reproduce with a Crowd server handling user management:
Same as above, but with the user and group coming from Crowd. Note that the equivalent of 'disabled' is 'inactive'.