Tracking your mail

What is mail tracking?

One of the most powerful advantages of using Lob is that you can track any individual mail piece as it moves across the entire print production and delivery process.
Each mail piece sent through Lob within the U.S. is printed with a unique identifying barcode, called the Intelligent Mail Barcode (IMb). Similar in concept to a "tracking number" that you receive when shipping a package via UPS or FedEx, if your mail was sent via USPS First or Standard Class, Lob will provide real-time progress through tracking information (“events”) related to every mail piece as it travels through the mail stream. Lob is able to do this because we are able to uniquely process proprietary data returned from our network of commercial printers and mail partners, in addition to surfacing USPS mail scans once the mail piece is handed off to USPS during its final leg of its delivery up to the recipient's mailbox.
With this comprehensive set of mail tracking data, we are able to surface events to customers via our webhooks feature in the Lob Dashboard, or the API by doing a GET request on a particular mail piece ID to see all up to date tracking events.
See our Webhooks guide for more details on how to set up webhooks. The full list of event types available for subscription can be found in our API documentation.

Mail tracking events

Tracking events

An "Event" is a notable action or occurrence that happens within the Lob architecture. "Tracking events" are a subset of all Events, and indicate where exactly is the individual mail piece in question progressing upon its submission to Lob, its production, and ultimately, its delivery to the end recipient.
Below is a list of each tracking event label and description, as recorded by Lob:
  • Received - The API call for the mail piece was made and received by Lob as a set of instructions for how the mail should appear. This includes parameters such as the size, content, mail type, etc.
  • In production - Mail piece instructions were dispatched to Lob's printer network and the request is now being printed/cut, soon to be handed off to the USPS for fulfillment.
  • "Mailed" - The “Mailed” tracking event is our confirmation that mail has been handed off from our printers. The ability to accurately surface this tracking event is a unique feature to Lob, and can be utilized to monitor Lob’s SLA adherence as well as provide auditable proof for time of mailing.
  • In Transit - The mail piece is being processed at the USPS entry/origin facility.
  • In Local Area - The mail piece is being processed at the USPS destination facility.
  • International Exit - The mail piece has been processed to ship to a destination abroad. This is typically the last scan a US-originated international mail piece will receive from the USPS.
  • Processed for Delivery - The mail piece has been greenlit for delivery at the recipient's nearest USPS postal facility. The mail piece should reach the mailbox within 1 business day of this tracking event.
  • Delivered - The mail piece has been delivered to the recipient’s address. The final scan is generated when the mail carrier's GPS unit leaves the delivery area.
  • Re-routed - The mail piece is re-routed due to recipient change of address, address errors, or USPS relabeling of barcode/ID tag area.
  • Returned to Sender (RTS) - The mail piece is being returned to sender due to barcode, ID tag area, or address errors.

Scanned events

Following production, all mail pieces will be handed off from our printers to USPS and will enter the USPS 'mailstream'. All subsequent events are subject to USPS accurately scanning the mail piece as it travels to its destination in the mailstream, hence called "scanned" events.
Lob does not have any control over the accuracy of scans, nor can Lob go back and reconcile scan events as it is purely a USPS-owned process.
For tracking events from USPS (i.e., all events listed after the "Mailed" event), expect to start seeing your first tracking event appear within:
  • 3 business days after your Send Date for First Class Mail
  • 4-5 business days after your Send Date for Standard Class Mail
While scans are not guaranteed by USPS, we do see scans on over 99% of our mailings. If more than 5 business days have passed and you don't have any tracking events, send an email to [email protected] and our team will be able to confirm whether the mail piece has been mailed.
In addition to accessing this mail tracking data via our API or Dashboard, you can receive real-time notifications by creating webhooks.

"Mailed" tracking events

The "Mailed" scan data is exclusive to Enterprise tier customers. Contact Sales if you want access to this feature.
The “Mailed” tracking event is USPS’s confirmation that they have taken custody of the mail piece from our printers. The ability to accurately surface this tracking event is a unique feature to Lob, and can be utilized to monitor Lob’s SLA adherence as well as provide auditable proof for time of mailing.
The “Mailed” tracking event appears at earliest two business days after sending your Lob API request. In some instances, it can take longer for this “Mailed” event to become visible, but when surfaced, it will accurately reflect the actual date of mail handoff from our printers to the USPS.
For non-Enterprise customers, the Mailed event in your dashboard view of tracking events will be greyed out as follows:
"Mailed" tracking event will be greyed out for non-Enterprise edition customers in your dashboard.

How to know if your mail was delivered

For First and Standard Class mailings, the "Delivered" scan is the last scan event that USPS provides. When your mail piece receives this scan event, this means that a USPS courier has delivered the mail piece.
Though we see scans for the majority of our mail, USPS does not guarantee every scan event for each mail piece. If a “Delivered” scan event hasn’t yet arrived for your mail piece, but you have received a “Processed for Delivery” scan, this indicates that USPS is expected to attempt delivery within one business day.
For international mailings originated in the US, see International Mail for details on tracking mail pieces abroad.

Delivery timelines & delayed pieces

Delivery times for mail will vary depending on mail class and destination:
  • First Class Mail: US domestic mail delivery typically takes 4-6 business days, and international mailings take an additional 5-7 business days.
  • Standard Class Mail: Delivery times can take anywhere from 7-21 business days. USPS does not provide delivery time guarantees for Standard Mail.
Delivery times quoted are estimates; Lob uses USPS as our primary carrier and USPS experiences delays from time to time. To see the most up-to-date status of your mailing, check the tracking information of your particular mailing.

Missing or out of sequence scans

All USPS scan events are dependent on the local postal offices and how they process/sort mail. Similarly, the delivery of those mail pieces is also under the full control of the local post office. We do not have added visibility or control over the actual mail pieces once they are handed off to USPS - we can only monitor their progress by surfacing mail tracking events that are visible on your dashboard.

Re-routed mail

If you receive a "Re-routed" scan, this indicates that USPS attempted delivery at the original address, but re-routed it because your recipient no longer resides at that address. In these cases, USPS will attempt to deliver to your recipient at their new address (if they filed a National Change of Address).

Undeliverable mail

If you received a "Return to Sender (RTS)" event scan, this indicates that USPS attempted delivery of the mail piece at the original address, was unsuccessful, and the mail is being re-routed back to the return address after being deemed undeliverable or misdeliverable as originally addressed.
This results in a yellow sticker being affixed to the mailing by USPS for tracking purposes, called a NIXIE label. The mail piece is treated as a new letter that is going to a new destination and will be tracked to the reroute location. This may be why the same mail piece may receive new scans after receiving the RTS event.
A multi-delivery attempt is translated into scans in “Delivery Attempt 1 and 2” below, compared to a standard delivery where the mail piece makes it to its final destination in a single attempt (Col 1):
Standard Delivery Process
Delivery Attempt 1
Re-Routed Attempt 2
In Production
In Production
In Transit
In Transit
Processed for Delivery
Return to Sender -->
In Transit [+Yellow Sticker]
Processed for Delivery
USPS may not consistently scan all mail pieces at every stage; Lob is only be able to capture and surface scans received from USPS itself.
Example of a USPS Return to Sender sticker (NIXIE label)
Because RTS scans are not necessarily an 'end-state scan', you should not track whether it was the last scan received when trying to calculate the percentage of RTS mail, as it may have been marked as such and still received additional scan events. Instead you should try calculating the percentage based on whether the RTS scan event was ever received, regardless of its place in the sequence of scan events.
Furthermore, we recommend you confirm the updated address with the intended recipient and submitting a new request to have it printed and mailed. There is currently no way to re-initiate an existing request in Lob.

Metered Mail

The minimum volume to qualify for Presort mail is 200 pieces (or 50 lbs) of Marketing Mail or 500 pieces of First Class mail, which is a USPS requirement. Some mail is sent out metered if that day's volume from one of Lob’s production team does not meet the minimum volume per mail type, as required by USPS. This means the mail pieces are not able to be batched with the other mail pieces and have to be mailed separately.
Historically these mailpieces have been difficult to track without a batch ID. But beginning July 12, 2023, the “Mailed” event for Metered mail is available in our webhooks for tracking events and included in mail counts within the Mail Analytics Dashboard.
We would also expect to populate the remaining tracking events for Metered mail, but this is not always guaranteed. Though we see scans for the majority of our mail, USPS does not guarantee scan events for every mail piece that goes through its sorting processes.

PO Box Mail

While we typically see all scans for the majority of our mailings, it is not unusual to see mail sent to a PO box with tracking that ends at the “In Local Area” scan event, even though the recipient has physically received the piece.
“In Local Area” scan indicates receipt and processing by the post office most local to the final delivery point. Typically the next scan would be “Processed for Delivery,” to indicate a mailpiece has been cleared for a final delivery attempt (and is likely loaded directly onto the mail delivery vehicle). However, a PO box does not need to be loaded onto a vehicle for the final delivery, as the PO box itself is located at the post office already. In this case, postal workers can simply hand-deliver the mailpiece to its final destination—so there will be no "Processed for Delivery" scan.

Exporting tracking events

You can also export all tracking events data into a CSV file. This can easily be done by accessing the Filters and Export buttons at the top of any list page.
From the list view, use the filters to select the type of mail items that you would like to export its tracking data. You can specify date range, metadata tags, and several other attributes that differ by form factor. Lob currently supports tracking no more than 250,000 mail items per export.
Export your mail piece data using the following steps:
  1. 1.
    Log into your Dashboard.
  2. 2.
    Click on the tab on the left sidebar menu of the type of data you want to export. For example, choose Letters.
  3. 3.
    Click on Filters and adjust your data settings in the top left corner button (Note: make sure you’re toggled to the correct Test or Live environment)
  4. 4.
    Click on the Export icon at the top of the page, and confirm your filter selections. Click yes to make a granular selection of associated tracking events.
5. Click Confirm to confirm you want to export the data. You will receive an email with a link to download the CSV file of your requested tracking events.

Return envelope tracking for reply mail

Enterprise edition customers can now access return envelope tracking for USPS Courtesy Reply Mail (for letters only). Once the returned mail piece enters the mailstream, the customer can start receiving notifications to tracking events via our webhooks.
For more information, see how to enable return envelope tracking, and how to view return envelope tracking events via webhooks.

Tracking for Registered & Certified Mail

Letters sent as Registered do not receive the same scan events as regular First or Standard Class mail. Registered Mail will instead receive a carrier tracking number and link, which is an add-on that will be available three (3) business days following the mailer’s send_date. This tracking number can be used to track the mailer via the carrier’s website.
Note that letters and checks sent in the Test Environment will not receive a tracking number.
If you decide to send Certified Mail through Lob, you will receive a carrier tracking number and tracking link retrievable via your Lob dashboard, which can be used to track the mail piece via USPS’s website. You can also track the mail via scan events within your Lob dashboard. Sometimes certified mail tracking will be available immediately, or as late as 3 days after sending the mail piece.
See Letters page for more information on tracking for Certified or Registered Mail.