Lob's API documentation is designed to be completely self-serve, but that doesn't mean we don't love hearing from you. If you can't find what you're looking for, we're here to help. Take a look at the FAQs below, send us an email or a tweet, and we'll get back to you well within 24 hours.
Standard Double Window Envelope Specs
Flat Envelope Specs
Letters and checks will be mailed in a standard double window envelope. Letters over 6 pages single-sided or 12 pages double-sided will be placed in a flat envelope instead.
You cannot edit any existing addresses via the dashboard or API request. You can delete the current address and add a new one with the updated fields. For more information on adding a new address please refer here.
Please reach out to support via email at firstname.lastname@example.org to re-invite a deleted user.
Lob currently does not offer a method to bulk upload addresses or mailings via the Lob dashboard. If you are looking for a tool to use our service without integrating with our API directly, we encourage you take a look at our various integrations and partner applications.
Typically, micro deposits take between 2-3 business days to hit your bank account.
You can find your Account ID through the following steps:
Lob's API products empower technology-focused companies to build powerful applications to control and scale their physical mailing. Instead of working through the complexities of direct mail, you can now access commercial grade printing & mailing infrastructure on-demand via a simple RESTful API.
Lob's customers range from Fortune 500 companies all the way to single developers working on side projects.
Whether you are sending one piece of mail or millions, Lob's products are built to be affordable and easy-to-use.
Integrating with Lob is easy! You can start mailing by following the steps below:
Each First Class postcard, letter, and check sent through Lob has a unique IMb barcode that gets scanned by USPS as it travels through the mail stream. You can access this scan event data via our API or Dashboard, or get notifications for them by creating webhooks. Below is a breakdown of each scan event label and description:
For First Class Mail, you will usually see your first scan event around 3 business days after the piece has been scheduled to go out.
Please note that IMb tracking data cannot be accessed via USPS's website and IMb tracking data not available for the following products:
Tracking events typically start appearing at earliest 3 mailing days after sending your API request (and in some cases can take longer). Please note that IMb scans are not guaranteed by USPS, but we do see scans on over 99% of our mailings.
International mailings will typically receive an "In Transit" scan, indicating that the mailpiece has been processed at the entry/origin facility. However, because delivery occurs in a foreign country outside of the control of USPS, international mailings do not receive scans beyond that.
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 Change of Address).
If you receive a "Returned to Sender" scan, this indicates that USPS attempted delivery at the original address, was unsuccessful, and the mailpiece is being sent back to the return address. In these cases, the address you mailed to was invalid. Please reach out to your intended recipient to update the address.
Letters sent as certified or registered and checks sent as overnight will not receive IMb scan events listed above. Instead, a carrier tracking number will be assigned when it becomes available 3 business days after the API request is received. A tracking number will not be populated for letters or checks created in test mode.
Your API Keys can be found in the "API Keys" tab of your Settings.
Requests sent with your test API key will not be actually printed/mailed. Use your test API key to try out the functionality of our service without worrying about being charged. Requests sent with your live API key will actually be printed and mailed.
Delivery times will vary depending on product and destination. Domestic delivery times are listed below:
International mailings will take an additional 5 to 7 days.
*Delivery times above 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 through a GET request or on your Dashboard.
You can invite team members from the "Team" tab of your Settings.
When inviting team members, there are three possible permission levels to choose from:
The best way to see what our products look and feel like is to send one to yourself! This way you will also get to see how the API works end-to-end.
Yes, the cancellation window on your account will delay the sending of all postcards, letters, and checks by the desired window. So if you want to meet a daily cutoff of 11AM and your cancellation window is 60 minutes, your cutoff time is actually 10AM. If you'd like to bypass your cancellation window for a certain send, you can do so by scheduling your mailing.
You can modify your cancellation window for postcards, letters, and checks individually in your Dashboard Settings. Keep in mind that any changes submitted on this page will only apply to mailings sent afterwards, not mailings that have already been submitted.
There are a number of third party tools that you can use to leverage our API. Below are a few:
Lob can mail all over the world. International mailings originate from the US and are mailed via USPS First Class Mail.
If you are looking to originate mail in a different country, please contact us.
We do cleanse your addresses in order to optimize for maximum deliverability. If you are on API Version 2017-08-14 or above, all US addresses created through
POST /v1/addresses and all inline addresses created through
POST /v1/letters, and
POST /v1/checks will be automatically standardized, cleansed, and verified through our CASS-Certified Address Verification system before being returned back to you in the API response. All international addresses will simply be standardized by being transformed to all uppercase. Afterwards, postcards and letters will be run through NCOA (National Change of Address), as these are requirements for sending USPS First Class Mail. This may result in the final mailing address being different from the ones you see in your API requests and Dashboard.