The AsyncHandler has auto-flush as always on which overrides the cool-down of the MailHandler push filter. There doesn't seem to be a way in the UI or the JBoss-CLI to turn auto-flush off. I can manually edit the logging.properties but editing the standalone.xml results in a validation error.

The idea of this enhancement would be to allow configuration of AutoFlush from the Web UI or at least include it setAutoFlush in the list of properties of the AsyncHandler so it can be toggled via the CLI.