java发送邮件【雅虎邮箱.com】本地测试通过服务器上却不行？

项目中有个java发邮件的功能，开始是gmail作为邮件发件箱的，后来要改成yahoo的 是.com的；
现在出现问题了，在本地测试可以发送邮件，上传代码到服务器上测试的时候却报错，
说是Could not connect to SMTP host: smtp.mail.yahoo.com, port: 25 连接超时什么的
请教各位....
下面是我的代码：
import java.util.Properties;

import javax.mail.Address;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class SendEmail {
public static boolean SendEmailTest(String ToEmailStr, String Title,
String Content, String FromEmaila) throws AddressException {
String FromEmail = "lostcrownservice@yahoo.com";
boolean fnt = false;
Properties props = new Properties();
Session sendMailSession;
Transport transport;
sendMailSession = Session.getInstance(props, null);
String smtp = "smtp.mail.yahoo.com";
props.put("mail.smtp.host", smtp);
props.put("mail.smtp.auth", "true"); // 允许smtp校验
props.setProperty("mail.smtp.port", "25");

try {
transport = sendMailSession.getTransport("smtp");
transport.connect("smtp.mail.yahoo.com", "lostcrownservice@yahoo.com", "******"); Message newMessage = new MimeMessage(sendMailSession);

// 设置mail主题
String mail_subject = Title;
newMessage.setSubject(mail_subject);

// 设置发信人地址
Address address[] = { new InternetAddress(FromEmail) };// 改变发件人地址
newMessage.addFrom(address);
// 设置收件人地址
newMessage.setRecipient(Message.RecipientType.TO, new InternetAddress(ToEmailStr));

// 设置mail正文
newMessage.setSentDate(new java.util.Date());
String mail_text = Content;
newMessage.setText(mail_text);

newMessage.saveChanges(); // 保存发送信息
transport.sendMessage(newMessage, newMessage.getRecipients(Message.RecipientType.TO));
fnt = true;
transport.close();
} catch (Exception e) {
e.printStackTrace();
fnt = false;
}
return fnt;
}
}