On Mar 29, 2014, at 5:51 AM, Eliot Lear <lear@xxxxxxxxx> wrote: > There is at least some value in retaining trace headers both for > debugging and anti-spam (mostly validating what one would expect to for > a given sender see), headers added by an MSA can entail privacy concerns > that (IMHO) outweigh debugging considerations. RFC 7044 (An Extension to the Session Initiation Protocol (SIP) for Request History Information) did a pretty nice job of addressing very similar privacy concerns.