Why am I getting an "email address is already in use" message when adding a new operator?

There are two potential reasons for this. You will need to check the following below:

1. Go to Settings > Operators & administrators and check this email address is not being used by another operator. Click Filters and include those that are disabled just to be sure.

2. The email address you are entering is currently being used by a customer. Operators and customers cannot share the same email address. You will have to provide an alternate email address or change the email address being used by a customer before adding your new operator.