Not starting with j2ee.jar in /lib direcotry

[Alexandre Alvarez Martini Santos]

Hello,
I put j2ee.jar in /common/lib directory and Tomcat4.1 did NOT start. 
It did not start when I put in jre/lib/ext as well.
Why?
I need some classes to use JavaMail.
Could you help me, please?
Thanks in advance,
al.