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Comparing ACE output with USPS website

Have you ever received different output from your ACE and/or one of our other address standardization softwares than you received from the USPS ZIP4 lookup website?  If you answered yes, then I will provide you some insight on why that can sometimes happen.

There are many times you may receive differing output in our ACE software vs USPS website lookup tool.  One common reason for this is CASS certified software (such as ACE), may standardize addresses differently due to their parsing and matching logic.  Therefore, you may notice that an address standardizes on the USPS website, however may not standardize when using ACE and/or one of our other address standardization products.

You may have the opposite situation as well.  An address may not standardize on USPS website but it does standardize using one of our address standardization products.  Unfortunately, there is no one authoritative source for how and address should standardize.  Therefore, if USPS, MERLIN and/or any other software vendor claim to be the final say, that simply is not correct.  It is my experience and opinion, that if I receive differing results between ACE vs USPS website for example, I always choose the ACE results as correct since it is CASS certified and uses one directory source vs potentially multiple sources. 

Another reason you may notice differing output, is you may have an address which a LACSLink updated address.  If you are not familiar with what a LACSLink updated address is, I will be blogging more about this subject in the very near future.

Lastly, you may also see an address assign on the USPS website but our address correction software indicates that the address is invalid or does not exist.  This could be the result of a new address not being entered in the US National directories yet and the new and/or updated address will be included in a future directory update.  When the USPS adds an address additional or change, it can sometimes take up to a couple months for the changes to be included in the directory shipments.

If you have an issue where neither our address correction software nor the USPS website assign a particular address believed to be valid, you should contact USPS Address Management Systems Office by sending an email to to report the issue.

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