Spring Mail Authentication Error

I am using spring 3.1 in my project and in order to send email, I am using spring mail. When I am trying to send an email, I aıways get this error:

org.springframework.mail.MailAuthenticationException: Authentication failed; nested exception is javax.mail.AuthenticationFailedException: No authentication mechansims supported by both server and client

My mail server does not require a username/ password and this error seems normal according to this fact. But the case is; I could not find a way to not to pass username/password in spring mail's org.springframework.mail.javamail.JavaMailSenderImpl class.

My config is :

<jee:jndi-lookup id="mailSession" jndi-name="${abc.app.mailSession}" cache="true"/>

    <bean id="jndiMailSender" class="com.abc.service.mail.JndiJavaMailService">
        <property name="session" ref="mailSession"/>
        <property name="defaultEncoding" value="${mail.defaultEncoding}"/>
        <property name="username" value="${abc.mail.username}"/>
        <property name="password" value="${abc.mail.password}"/>
        <property name="mailMasterAdress" value="${abc.mail.mailMasterAdress}"/>
    </bean>

Mailserver is in weblogic and it's configs are:

mail.smtp.host=10.200.123.135 mail.transport.protocol=smtp

Any ideas?