sorry , this sugest duplicates http://glpi.userecho.com/topic/1024913-pouvoir-envoyer-un-mail-a-des-personnes-differentes-lors-de-lexpiration-dun-contrat/

( did not find keyword contract)

duplicates :

http://glpi.userecho.com/topic/1044048-contract-associate-actors-technicians-groups-observers-for-notifications-searches/