Sorry about the trouble my VPS has been causing.
After I talked to my system admin, it appears the outbound UDP flood was caused by one of the PHP coded business sites hosted on the VPS has security exploit, a hacker uploaded a PHP UDP flood attack script and used it to attack other servers.
I would like to ask you kindly unsuspend my account and reinstall the VPS so the hacker no long able to use attack script.
I will use iptables to block all UDP traffic in the future.
I can assure you my VPS will not cause anymore problems.
Please give me another chance.