Spring integration, auto wiring failed (null) - spring

Question

I am using spring integration to listen to emails.
I have a Spring component named mailService that is instantiated and the method handledMail is called each time a new email arrives.
I wanted to add some more code into EmailService like this:
#Component(value="mailService")
public class EmailService {
#Autowired
private ApplicationContext applicationContext;
My issue is that I have a null pointer exception when accessing applicationContext
Do you have any idea where does this can come from? My applicationContext.xml file was read. All the channels have started and the emailService component has been instantiated by Spring. Should I add something specific in the configuration?
Some more code:
#Component(value="mailService")
public class EmailService {
private final static Logger logger = Logger.getLogger(EmailService.class);
#Autowired
#Qualifier(value="mailSender")
private JavaMailSenderImpl mailSender;
public EmailService() {
initContext();
}
private void initContext() {
RuleManager ruleManager = (RuleManager) applicationContext.getBean("localRuleManager");
ContextEvidence evidence = new ContextEvidenceEntry(EvidenceType.ROLE, new String("Front Office"));
ruleManager.addMultipleEvidence(evidence);
}
I have a null pointer exception in the first line of initContext, applicationContext being null
The listening channel is started as below;
final ApplicationContext ac = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
DirectChannel inputChannel = ac.getBean("receiveChannel", DirectChannel.class);
It was working fine before I added the applicationContext and the initContext() lines.
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mailService' defined in file [XXXX/EmailService.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [XXXXEmailService]: Constructor threw exception; nested exception is java.lang.NullPointerException
Thanks
Gilles