I’m wondering what happens if I import a file without all the columns included? I would assume the missing data would be left alone and not updated. I noticed when I uploaded a file with Email Address included and First Name and Last Name missing, the first name and last name fields were populated with the Email Address. I had to go back and fix this, as it’s not what I imagined would happen.
Hi @sarahiswright,
Thanks for reaching out!
I moved your reply to a new post to give it more visibility as you had posted on an older thread 
We always suggest creating new posts when looking for assistance from the Community.
Our contact records pull the first and last name properties as the primpary display property. If these values aren’t filled, as is the case with your imported contacts, HubSpot will pull the contact’s email as the identifier instead and populate the first and last name fields with the email address.
I would suggest including the First and Last name in the import if you are looking to create new contacts, and if you are looking to update contacts with an import, you can export existing records and use the Record ID as a unique identifier.
I hope this helps!
Best,
Kristen
Hi Kristen, that makes sense. Appreciate your clarification!