Why do I have a contact called Unknown Unknown in my contact list?

In Aero, email addresses belong to Contacts (people), not Companies (entities), and a contact first and last name is required for each email address. 

Either during your sync with QuickBooks Online or during a customer import, one or more companies were imported with a default email address and no contact name so a contact named "Unknown, Unknown" was added to your Aero Database.

To attach an email to a real Contact:

1. Create a new Contact without an email address. You can choose a default Company from the drop-down if you would like. How to create a new contact
2. Go to Customers > Email Addresses, find the email address that should be associated with the contact you just created, and edit it. Choose the new contact from the contact dropdown then save and close. How to Edit an Email Address
3. If you want that new contact to be the default for a Company, edit the Company and choose the Contact from the Contact dropdown. How to edit a Company