CSV File Import/Upload
When uploading a csv file of users to create a segment, do we also have to include their external ID or can we just have their email, first name, last name?
The use of the external ID is to allow you to identify them across all devices. I would recommend it, it can also reduce the rate of duplication therefore reducing your data point usage.
tiannaterrell1 external_id or user_id is a mandatory field. You can't upload your CSV without it. If you don't have external ids, you'll need a user alias for each user.
Some companies let email be their external user id, but it's not a good practice for security reasons. Best practice is using uuids.
