Cannot send email notification

I check into the log file, find the following:

14:38:39:703 Notifications: Exception occured while sending mail at:
javax.mail.MessagingException: Could not connect to SMTP host: 192.168.10.200, port: 25;
nested exception is:
java.net.ConnectException: Connection timed out: connect
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1008)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:197)
at javax.mail.Service.connect(Service.java:233)
at javax.mail.Service.connect(Service.java:134)
at com.adventnet.me.opmanager.server.util.MailServerHandler.checkMailServer(MailServerHandler.java:90)
at com.adventnet.me.opmanager.server.NotificationThread.notify(NotificationThread.java:282)
at com.adventnet.me.opmanager.server.NotificationThread.run(NotificationThread.java:244)

I'm sure the connection to SMTP server ok, I can send email using outlook express on the same host.
Can someone tell me how to fix it?