Hi,
If you would like to involve your custom data to subscribers you would need to re-write the code in:
<web site folder>\CMSModules\Newsletters\Tools\ImportExportSubscribers\Subscriber_Export.aspx.csPlease find the line about 90:
subscribers = SubscriberProvider.ExportSubscribersFromSite(newsletterIds, CMSContext.CurrentSite.SiteID, true);
you may add your own function here.
You can access the table:
Newsletter_Subscriber and select all data you need. The output of this function should be a string which contains rows for particular subscribers in format:
attribute1;attribute2;attribute3;attribute4\n
Best regards,
Helena Grulichova