This script fixed this problem for me
#!/bin/sh
#remove the default GNU JavaMail JAR because it does not support SMTP
#
if [ -f "/var/lib/tomcat5/common/lib/[javamail].jar" ]
then
rm /var/lib/tomcat5/common/lib/[javamail].jar
echo "file removed"
else
echo "no file to remove"
fi
notes:
1) you need to return success from this script or the deployment / redeployment will fail.
2) This is only necessary on the tomcat 5.5 application tier instances as the tcServer ones have a different set of JARS (not sure about other variants as I've only tried these two)