ant,mail的问题?

[ZQGet]

Buildfile: build.xml

mail:
[mail] Sending email: null
[mail] Failed to send email

BUILD FAILED
X:\Pinball\PINBAL~1\SAMSUN~1\build.xml:6: Problem while sending mime mail:

Total time: 1 second

我使用ant来发送邮件,缺出现了上面的错误,请问是怎么回事?
我的build.xml文件:

<project name="ant_test" basedir="." default="mail">
<target name="mail" description="test mail">
<mail mailhost="smtp.163.com"
mailport="25"
user="zqget123"
password="123456">
<from address="[e-mail]"/>
<to address="[e-mail]"/>
<message>this is a test mail!</message>
</mail>
</target>
</project>

[Mybeautiful]

把mail.jar;activation.jar放入Ant home/lib中.