If the system tells you that the email address you're trying to add has already been taken, that means that the email address is in your account as either an Active or Archived user. Kudos identifies users by their email addresses, and while users can be in more than one organization's account with the same email address, the same email address cannot be used twice within the same account. Even if a user is archived, their email address cannot be used again to add a new user.
To solve this problem go to Admin ⚙️ > User Admin > Users, then do the following:
Click in the search field to open up the filters. Click the first menu to change the "Active Users" filter to "Archived & Active".
Type the email address that you are trying to use in the search field and select the correct name from the list that will auto-populate.
"Activate" that user. You're now able to edit the user's information in any way.
If you use a generic email for a user (for example, firstname.lastname@example.org) and have a new user take over the role, you may want to keep the previous user information intact for reporting purposes. In this case, you will want to edit the user information as shown above, but leave the name and employee information as is. Simply update the email address to include a modification (it does not need to be a valid email address as the account will not be used) - for example, you could set the email to email@example.com. This will make the valid email available for use for the new employee when you add them.
We hope this helps! If you have any questions, please reach out to us at firstname.lastname@example.org and one of our friendly team members will be happy to assist you.