Hi @DinahJones
As long as the CSV file matches the expected format, it should import all OK.
Unfortunately there isn’t a way to import just email addresses for existing clients, but you can add them by going into the client view individually and adding a contact.
Was your file in the format at the link above? If so, I’m happy to take a closer look for you - please feel free to send me a private message (click my name and then ‘Message’), and upload the file.