What is 'later on'?
Thanks for your reply!
by first time, i mean when the webapp is deployed on the server, I found that my custom notifier and email address resolver are instantiated. But when the actual mail event is fired during the course of the workflow(later on :) ), that time jbpm's mail.class is invoked, which uses default of from-email-address as jbpm@noreply, which throws an invalid address error.
By keeping jbpm.cfg.xml file directly in classpath, my notifier was picked up alwayz, but as long as i kept it as j-workflow/jbpm.cfg.xml, the default kept getting used, even though this file was present in the classes of my webapp.