It's solved:
I was trying to deploy on a Windows OS, and the Catalina log was rising advise: "WARNING: This software has never been tested under your OS"
So, I deployed in a linux Tomcat and as soon as I added the CATALINA_HOME and the jars in the bin of the tomcat, it worked!
Despite the requirements of jwebmail are not specifying a system, wouldn't advise to try it on Windows, I don't think I'd ever succeeded
thanks to all!