Why not notify instead?

Instead of using bounce/reject, which could be seen as one among
several notifications, you could instead define a notify command in
Sieve. The notify command would then encapsulate all notifications
including address change, denial of delivery and such.

Like this:
if header "from" contains "enemy"
{ notify-originator delivery-denied "Keep your messages to yourself!"; }

-- 
Hälsningar/Regards

Tomas Fasth <tomas(_dot_)fasth(_at_)twinspot(_dot_)net>
Tel: +46-13-218-181 Cel: +46-708-870-957 Fax: +46-708-870-258
EuroNetics Operation, Mjärdevi Science Park, 58330 Linköping, Sweden
(TwinSpot Network is a subsidiary of EuroNetics Operation)