Set Email form to readonly

Hello everyone,

I have added custom status code values to the Email entity. On setting of these custom status code, the form becomes editable. On these statuses i want the form to freeze. I tried setting the fields to readonly but CRM throws error if any of the field does not have value. Can anyone of you help me achieve the requirement. Any pointers would be appreciated.

Kind regards,

Thank you

Mehaboob