I can't send lots of recipients by javamail

I can't send lots of recipients by javamail

I'm trying to send notification mail to recipients by javamail, but got
some error. I looed into this by debug and found out that the system can't
send more than 100 recipients.
Tue 8/27/13 01:05:42: RMI TCP Connection(11)-127.0.0.1: 250
Kelly.Ye@amkor.com... Recipient OK Tue 8/27/13 01:05:42: RMI TCP
Connection(11)-127.0.0.1: RCPT TO: Tue 8/27/13 01:05:42: RMI TCP
Connection(11)-127.0.0.1: 250 Qiang.Wu@amkor.com... Recipient OK Tue
8/27/13 01:05:42: RMI TCP Connection(11)-127.0.0.1: RCPT TO: Tue 8/27/13
01:05:42: RMI TCP Connection(11)-127.0.0.1: 250 Lingfang.Ma@amkor.com...
Recipient OK Tue 8/27/13 01:05:42: RMI TCP Connection(11)-127.0.0.1: RCPT
TO: Tue 8/27/13 01:05:42: RMI TCP Connection(11)-127.0.0.1: 250
Xinping.Han@amkor.com... Recipient OK Tue 8/27/13 01:05:42: RMI TCP
Connection(11)-127.0.0.1: RCPT TO: Tue 8/27/13 01:05:42: RMI TCP
Connection(11)-127.0.0.1: 250 Rong.Dong@amkor.com... Recipient OK Tue
8/27/13 01:05:42: RMI TCP Connection(11)-127.0.0.1: RCPT TO: Tue 8/27/13
01:05:42: RMI TCP Connection(11)-127.0.0.1: 250 Canny.Zhang@amkor.com...
Recipient OK Tue 8/27/13 01:05:42: RMI TCP Connection(11)-127.0.0.1: RCPT
TO:
as you see, it was stopped. just send less than 100 recipients.. please
advise me...