Yes. You can update values, and add new attributes for existing users. All CSV uploads require you to have a column with unique identifier (Customer ID). 

A few things to note:

  • You can't update the customer id by 
  • If you leave a field blank when updating existing columns, it will result in overwriting values to unknown.
  • If you update existing customers and they match the criteria for an active  automated campaign, they will immediately be sent a postcard for that campaign.

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