Yes. The problem with the default listener is it cobbles up and places the entire file into the message ie: server ram for delivery. Since our files come from main frames and can be giga bytes in size this isn't a suitable solution. Which is fine the custom composer class was designed to handle this situation by delgating message composition to a plug-in class. The root of the problem is that the custom composer class configuration doesn't work and is the subject of the Jira. I have worked around this by creating a custom message listener that indeed calls my message composer.
ok. Thanks for bringing this up. As a result of it, this just got fixed on the trunk. See http://jira.jboss.com/jira/browse/JBESB-380.
--Kurt