Address Verification can identify addresses that do not provide a door or entry point that the postal carrier can access. A DNA address might not provide a door for mail delivery, or the mailbox might reside behind a locked gate.

To identify DNA addresses, Address Verification introduces the DPV_DNA field. The DPV_DNA field can contain the values Y or N, or the field can be empty. Address Verification can update the DPV_DNA field when you verify United States addresses in certified mode and when the address has a DPV return code of Y, S, or D. Address Verification returns Y in the DPV_DNA field for a DNA address and returns N otherwise. Address Verification does not update the DPV_DNA field in other process modes.

Address Verification can identify addresses that do not provide a reliable mailbox or reception point for mail. The United States considers an address that cannot reliably accept mail to be a No Secure Location (NSL) address.

For example, a storefront might be non-secure if the store is closed on one or more weekdays and does not provide a mailbox to receive mail on those days.

To identify NSL addresses, Address Verification introduces the DPV_NSL field. The DPV_NSL field can contain the values Y or N, or the field can be empty. Address Verification can update the DPV_NSL field when you verify United States addresses in certified mode and when the address has a DPV return code of Y, S, or D. Address Verification returns Y in the DPV_NSL for a NSL address and returns N otherwise. Address Verification does not update the DPV_NSL field in other process modes.