SUPPRESS will NOT add duplicate emails to the same list when imported. When email addresses are uploaded, we will check to see if they exist on the list. if the email exists, it will be flagged as a duplicate and will NOT be added.
*Please note - the only exception would be if you create a new Opt-Out List and the data you are importing for the first time has duplicates. In this case, the duplicates will be loaded because the email addresses do not currently exist on the Opt-Out List to validate duplicates.
If you have further questions please contact: firstname.lastname@example.org