Spring Integ - Flow which can cause rejection messages to build up against the errorChannel

slowtasks.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns:beans="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://www.springframework.org/schema/integration"
	xmlns:task="http://www.springframework.org/schema/task"
	xmlns:int-jmx="http://www.springframework.org/schema/integration/jmx"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
		http://www.springframework.org/schema/integration/jmx http://www.springframework.org/schema/integration/jmx/spring-integration-jmx.xsd
		http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task.xsd
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
	<context:mbean-server/>
    <context:mbean-export/>
    <int-jmx:mbean-export/>
	<channel id="input">
		<queue capacity="5"/>
	</channel>
	
	<channel id="output">
		<queue capacity="5"/>
	</channel>
	
	<channel id="errorChannel">
		<queue/>
	</channel>
	
	<service-activator expression="payload + '.Hello' " input-channel="input" output-channel="output">
		<poller fixed-delay="20"  max-messages-per-poll="10" task-executor="taskExecutor"></poller>
	</service-activator>

	<task:executor id="taskExecutor" pool-size="10" queue-capacity="10"/>

</beans:beans>