In the process of adding a contact or an agent, an admin may encounter the error message that the email has already been taken. This means that there is already an account associated with the entered email address.

I received the error message as I was trying to add an agent.

1. From Admin Settings, click on the Agents tile, then click on all users as opposed to staff only.
2. This will bring up a list of all users. Search for the email address here. 
3. Click on the profile. Look at the role of the user. If it is a user role, then you'll need to change the role to an agent role.
4. Click on the pencil icon to edit the profile.
5. Change the role from user to one of the agent roles.

I received the error message as I was trying to add a contact/user.

1. From Admin Settings, click on the Agents tile, then click on all users as opposed to staff only.
2. This will bring up a list of all users. Search for the email address here. 
3. Click on the profile. Look at the role of the user. Likely, this will have an agent role. If so, then the role will need to be changed from an agent role to a user role.
4. Click on the pencil icon to edit the profile.
5. Change the role from agent to user.

Related Resource: Different User Roles in Mojo