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 so a contact named "Unknown, Unknown" was added to your Aero Database.
To attach an email to a real Contact:
- 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
- Find the Contact you just created and edit it. Choose the correct email address from the Email Address dropdown. How to edit a contact
- Go to Manage > Email Addresses, find the email address you chose in step #2, and edit it. Choose the Contact you just created from the contact dropdown. How to Edit an Email Address
- 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