It might be possible that some of the (contact) data in iController is not the same as the data in your accounting program.
The debtor sheet gets updated only when there are open invoices for that debtor. An archived debtor won't have data imported in iController until there is an open invoice again.
- Day 1: You change the e-mail address of debtor X in the accounting program.
- Day 2-3-4: The outdated e-mail address is still visible in the debtor sheet.
- Day 5: Debtor X gets an open invoice.
- Day 5 after data export/import: e-mail address has been changed in iController.