The following letter tracking codes are authored by USPS and used in the Certified Mail Labels Summary Tracking report.
Code & Meaning:
I - In transit
D - Delivered
N - shipping label prepared/not indicate receipt
U - Unable to deliver
1 Not Found
0 Found – No Status
A - Accepted Logged at USPS
C - Customer Recall
E - Dead Letter
F - Forwarded to New Address
I - Scanned in Route
L - Notice Left for Recipient
N - New Item
O - Out for Delivery
P - Available for Pickup
R - Returned to Sender
U - Undeliverable
V - Delivery Status Not Update
X - Other
