To find any and all contacts within your account that do not have an email address, start by navigating to your Contacts menu. From here:

• Click on the Contact List tab.
• Click the Filter button to add a new filter.
• Click on the Select New Filter dropdown, and choose Field: Email Address
• In the condition box, choose does not have a value.
• Click Apply Filters.

You will then see a list of all contacts in your account that do not have an email address.

You can download this list as a .csv file by clicking the Select all box (1) (if the list carries over more than one page, click the Select all xx contacts link that appears after ticking this box) and then the download link (2).