An email can only be saved in the system once. This means that you cannot have clients sharing the same email or a staff member also being a client with the same email.

If you cannot see the client or staff already using the email, they are likely to be inactive or archived. Tick the “show archived” and “show inactive” checkboxes in the top right hand corner of the admin/client or admin/staff page to see them.

You can get around the problem of not being able to use the same email address by adding "+1" just before the @ in the new email address.

E.g. to send to hello@collums.co, use hello+1@collums.co

This solution works for most major email platforms but please note, it may not work in all cases.