Implementations of draft-ietf-sieve-refuse-reject-07 ?

Are there any Sieve implementations that follow 
draft-ietf-sieve-refuse-reject-07?

I am quite interested in replacing my existing per-user SMTP-time
rejection mechanism based on courier-mta's mailfilter with something
that will hopefully wind up as a standard Sieve-based method.

I've seen reference to Sun's implementation.. is this available as open
source, or as a proprietary product?