can not support transaction

[maplye]

event('mailRegistration', user, [fork:false]).waitFor()

@grails.events.Listener(proxySupport=true)
def mailRegistration(User user){
    def u = Config.get(2)
    u.val = "1"
    u.save()
    log.debug "listen the mailRegistration event"
    log.debug user
    throw new SxspException("send mail error")
 }

I used grails 2.3.7, and the Config id=2 val value changed to 1. the transaction don't worked done.