Notification conditions for multiple mandatory check fields

Hello,
I would like to setup a notification to email the assigned employee which fields have not been filled in yet so that we can save entries without making fields mandatory. So for example if I have fields in customer like:

phone_number
fax_number
email
street_address

And I enter the phone number and save it, it should send a notification to the assigned employee that this customer still needs a fax number, email, and street address added.

The idea is to be able to enter and save new customers and have them “frozen” by default at first, and can only be unfrozen once all information fields (like phone, fax, email, and address) have been filled out.

I have tried with the conditions but cant seem to make it work. Thanks for any help!