CCK sends out Blank fields

I've taken over managing a site for someone that uses a CCK form to receive information from site users.

The trouble is that the form has a whole host of optional fields (e.g. Date you started...), that most users will not be completing. The result is that the site Admin receives a long email with the titles of all of the fields, even if not filled-in, e.g.

First name: Man's first name
Last name: Man's last name
Date of birth: January 1, 1970
Home phone: Home phone
Work phone: Work phone
Mobile phone: Mobile phone
Address 1: Address 1
Address 2: Address 2
Address 3: Address 3
City/Town: City/Town
County: County
Postcode: Postcode

Even if I remove the default values, they still get sent something like:

Home phone:
Work phone:
Mobile phone:
Address 1:
Address 2:
Address 3:
City/Town:
County:
Postcode:

Is there a simple way to edit it so that they are not sent blank fields?