<!-- Using a JNDI named JavaMail Session object defined by the -->
<!-- session attribute. -->
<mt:mail session="java:/comp/env/session" to="foo@home.net"
from="bar@home.net" subject="mail taglib">
<mt:message>[body of message]</mt:message>
<mt:send/>
</mt:mail>

When using this syntax in Resin 2.1.8, get a NamingException

Solution is to use 

java:comp

*not*

java:/comp

Is the documentation incorrect?  Not sure what JNDI standard is.