A small number of customers were affected by a deployment to a single facility wherein the configuration did not contain all legacy domain names for various services.
For example, the official domain name for the US Street API service is:https://us-street.api.smartystreets.com/
An older (legacy) domain name for the same service is:https://api.smartystreets.com
Further, this same issue touches a handful of other services including:
us-extract.api.smartystreets.com (legacy: extract-beta.api.smartystreets.com)
us-autocomplete.api.smartystreets.com (legacy: autocomplete.api.smartystreets.com)
The issue was manifest from 9:00 AM Eastern Time until 10:15 AM Eastern Time, at which time the configuration was rolled back pending review. Further, various automated tools which conduct systems test are being updated to verify legacy domain name compatibility.