Uploaded segment identifiers and leading zeros

For school administrators using GiveCampus Outreach. Controls can differ between the classic email editor and the newer Composer editor.

Segment uploads trim external_id and match it exactly to the stored constituent unique identifier. This process does not apply school minimum-ID-length padding. Preserve IDs as text, verify the full value including leading zeros in the actual CSV, and replace/re-upload corrected audience data through the supported workflow. Confirm matched constituent records before personalization. Spreadsheet display formatting alone may not preserve zeros in an exported CSV.