Yes. For Enterprise edition customers, Lob offers return envelope tracking for their USPS Courtesy Reply Mail services. Currently, tracking information is only available via webhooks.
To access this feature, enterprise customers need to send an API request for a letter with 'return envelope', 'return address' and 'perforated page' options completed. The letter and a return envelope (#9 return envelope) will then be sent to the customer in an outer envelope (#10 envelope).
Once any returned envelope enters the mail stream, the Intelligent Mail Barcode (made visible through the return envelope window) will be scanned by USPS, which will generate mail tracking data that can be accessed via our API, which customers can receive notifications via webhooks.