Custom columns in uploaded segments

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

Do not assume that accepting a CSV header means its values become available for personalization. The segment upload validator recognizes custom_ headers, but the segment import stores standard identity/contact fields and does not carry those custom values into segment members. Direct Outreach recipient uploads have a separate process that does read custom merge-token values. Use that supported direct-upload workflow for message-specific personalization, or verify the appropriate constituent-data import when the values belong in CRM/custom fields. A segment membership upload is not a general constituent custom-field update.