Product Update: Free Verification of Mailing Addresses

Free Verification of Mailing Addresses

Accurate addresses are important. In fact, verifying addresses before you mail is a necessary part of sending mail at scale to optimize the efficiency and accuracy of your mail delivery.

Whenever you send a mailing through Lob, you reap the benefits of free, accurate address cleansing and verification powered by our CASS-Certified Address Verification API. Upon creation, all US addresses will be automatically standardized, cleansed, and verified through our US Address Verification API before being returned back to you. All international addresses will simply be standardized by being transformed to all uppercase to conform with USPS standards.

Standardization and Verification

Depending on what business logic you’d like to take based on your verification result, you can toggle your US Address Strictness Settings in your Dashboard. There are 3 possible Strictness Levels:

  • Strict: Only US addresses that Lob and the USPS deem deliverable can be successfully used to send postcards, letters or checks.
  • Normal: Postcards, letters, and checks will be created for addresses that Lob and the USPS deem deliverable, as well as addresses for which secondary information is extraneous or missing.
  • Relaxed: All postcards, letters, and checks will be successfully created and mail delivery will be attempted, regardless of address validity.

Ultimately, this allows you completely control the destiny of your final pieces. Only want to send to addresses that are guaranteed to be deliverable? Pick “Strict” mode. Confident that your addresses are right and want us to mail them out anyway? Use “Relaxed” mode. We want to give you the power to decide when Lob should be sending mail or when we should be rejecting based on deliverability. Ultimately, this reduces the amount of undeliverable mail you send and saves you money.


As always, please reach out to us with any comments, questions, or feedback you may have. We love hearing from you and are always improving our offerings based on your thoughts!