Parameswary thanks for raising the request, while we evaluate, kindly provide additional information, assuming the request is for Reader Groups - Self Registration.

In the import file, fields such as domain values, domain restriction type should be mentioned as well which again would be a manual input. Since the email domain supports only either Allow or Block, existing list might be overridden. Is this the expectation from the customer end?

Based on further user-engagement we will move forward further. Thank you.