I am uploading a static list of people who are getting a paper mailing, so that I can track the number of paper invites that respond to the Marketo landing page.
The list I am uploading doesn't include the email address, but If members of this static list already exist in Marketo, which they may, will Marketo add the email address to the static list record?
Marketo uses EMAIL as one unique identifier. If you are importing a list without email addresses, it will create a new contact with the email address empty. Include the email address to associate with a contact that already exists in the database.
There's not a lot of benefit to importing leads without an email address as when they do submit the form on your landing page, a new lead will be created. If you do import the email-less list, a third party tool such as RingLead would be required to find potential matches and their email address based on name and other data such as phone number, company name, etc. and merge them.