Values need to be seperated by commas and subscribers by newlines. If there are more than just an email column, a header row with the token names is required. In-token commas and newlines require the token to be wrapped in double quotes. In-token double quotes have the same requirement but also need to be escaped with another double quote.
firstname.lastname@example.org,"token with, a comma","token with a "" single doublequote","token with a