You can export subscriber sets to comma-separated value (CSV) files. In the Subscribers screen, you can preview and export subscriber sets. You can export all rows in a set; the maximum number of rows you can preview is 2000.
Exporting lets you create subscriber sets by merging multiple files, and save the combined content. A subscriber set may have been created as an empty set, and later populated by applications, using options such as opt-in, subscribe, or log for reporting. Exporting lets you transfer data to the system of record, for reporting. You can also develop an automated system to perform the transfer, using applications and custom states.