自动发送电子邮件程序

为什么只能发公司的邮件成功,发给其他邮件系统就不成功?
package javamail;

/**
* @author Administrator
*
*/
import javax.mail.*;
import javax.mail.internet.*;
import java.util.*;

//import UploadFile.*;
import org.apache.log4j.*;

public class AutoSendMail {
public AutoSendMail() {
}

// public Log4J log4j = new Log4J();
String host = null;
String username = null;
String password = null;

public void setHost(String host) {
this.host = host;}

public void setAccount(String username, String password) {
this.username = username;
this.password = password;
}

public void AutoSendMail(String from, String to, String cc, String subject,
String content) {
Properties props = new Properties();
props.put("mail.smtp.host", "aa.test.com.cn");
//props.put("mail.smtp.auth", "true");
try {
Session mailSession = Session.getDefaultInstance(props,null);
mailSession.setDebug(false);
Message message = new MimeMessage(mailSession);
message.setFrom(new InternetAddress(from));
message.addRecipient(Message.RecipientType.TO, new InternetAddress(
to));
message.addRecipient(Message.RecipientType.CC, new InternetAddress(
cc));

message.setSubject(subject);
message.setHeader("Dear All", "");
message.setText(content);
message.saveChanges();

Transport transport = mailSession.getTransport("smtp");
transport.connect(host, username, password);
transport.sendMessage(message, message.getAllRecipients());
transport.close();
} catch (Exception ex) {
// log4j.error.error("Auto Send Mail Error : " + ex.getMessage());
System.out.println(ex.getMessage());
}
}

public void AutoSendMail(String from, String to, String subject,
String content) {

Properties props = new Properties();
props.put("mail.smtp.host", "smtp.163.com");
//props.put("mail.smtp.auth","true");
//props.put("mail.smtp.auth", "true");
try {
Session mailSession = Session.getDefaultInstance(props);
mailSession.setDebug(false);
Message message = new MimeMessage(mailSession);
message.setFrom(new InternetAddress(from));
message.addRecipient(Message.RecipientType.TO, new InternetAddress(
to));

message.setSubject(subject);
message.setHeader("Dear All", "");
message.setText(content);
message.saveChanges();

Transport transport = mailSession.getTransport("smtp");
transport.connect(host, username, password);
transport.sendMessage(message, message.getAllRecipients());
transport.close();
} catch (Exception ex) {
// log4j.error.error("Auto Send Mail Error : " + ex.getMessage());
System.out.println(ex.getMessage());
}
}
public static void main(String args[]){
AutoSendMail send = new AutoSendMail();


}

}

把身份验证带上啊

身份验证带上好象也不行呢,不知那还有比较好的例子