spring2.5 javamailsender locked in javax.mail.service.connect

spring2.5 javamailsender locked in javax.mail.service.connect

I used spring 2.5 JavaMailSenderImpl to send mails. When I sent more than
10,000 mails, my program got blocked. This was the thread information
showed by jstack: "pool-4-thread-6" prio=10 tid=0x000000001b94d800
nid=0x44fb runnable [0x0000000041901000] java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.socketRead0(Native Method) at
java.net.SocketInputStream.read(SocketInputStream.java:150) at
java.net.SocketInputStream.read(SocketInputStream.java:121) at
com.sun.mail.util.TraceInputStream.read(TraceInputStream.java:97) at
java.io.BufferedInputStream.fill(BufferedInputStream.java:235) at
java.io.BufferedInputStream.read(BufferedInputStream.java:254) - locked
<0x00000000e6e2d170> (a java.io.BufferedInputStream) at
com.sun.mail.util.LineInputStream.readLine(LineInputStream.java:75) at
com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:1440)
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1260) at
com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:370) at
javax.mail.Service.connect(Service.java:275) at
org.springframework.mail.javamail.JavaMailSenderImpl.doSend(JavaMailSenderImpl.ja
va:389) at
org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java
:342) at
org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java
:338)
perhaps this program was blocked beceuse of the mail connectionCbut I
deployed out-time in the spring config file: 25000
25000 program should throw an exception when time exceed.but it still gets
blocked!! Is anyone who knows the reasons?