When you trying to invite your support team to Kayako (see Adding and Editing User Accounts) from the Admin area, you may run into the below error message:
There is already a user with this email address:
If you are experiencing this error, it means that the person you are trying to invite has already created an account on Kayako at some point, but they may not have a full Agent or Admin permissions.
You can make sure they have the right permissions by searching for them in the Agent area, and updating the Role field in the sidebar, as shown below:
Refer to Assigning User Roles to Your Team and Customers for more information on user roles in Kayako.