RFC Status Change : Change the status of ADSP (RFC 5617) to Historic
ADSP has garnered almost no deployment and use in the 4 years since its advancement to IETF Proposed Standard. While there are implementations in code, there is very little deployment and no evidence of the benefits that were expected when the standard was written.
There is, however, evidence of harm caused by incorrect configuration and by inappropriate use. There have, for example, been real cases where a high-value domain published an ADSP record of "discardable", but allowed users on their domain to subscribe to mailing lists. When posts from those users were sent to other domains that checked ADSP, those subscriber domains rejected the messages, resulting in forced unsubscribes from mailman (due to bounces) for the unsuspecting subscribers.
Assurances that are provided by ADSP are generally obtained out of band in the real Internet, and not through ADSP. Current deployment of ADSP is not recommended.