Provide your web URL is the simplest way to let people view your applet.
If you want to add applets into the message body. Copy applet tag (one single line) into message body, and modify the codebase (point to your server:

I have add applet from the above URL to here.

The code I have added is
<applet code="_examples.weelookangresistance07.weelookangresistance07Applet.class" codebase="" archive="../../../_library/ejsBasic.jar,weelookangresistance07.jar" name="weelookangresistance07" id="weelookangresistance07" width="750" height="550"></applet>