My index.xhtml page contain this and more other little thing like footer, header,menu etc... :
index.html contain :
<h:head/>
<h:body>
 <p:layout fullPage="true">
  <p:layoutUnit position="center" >
  <h:panelGroup id="content" layout="block">
    <h:form id="contentform">
<!-- Cas page contact == page affichée lors du clic sur contact -->
     <h:form id="contact">
      <h:panelGroup rendered="#{navBean.page == 'contact'}">
       <ui:include src="contact.xhtml" />
      </h:panelGroup>
     </h:form>
    </h:form>
<!--Fin de gestion des cas possible -->
 </h:panelGroup>
</p:layoutUnit>
<!-- Fin layout central --> 
 </p:layout>
</h:body>
I'm using JSF 2.1 and PrimeFaces. I have the following command button on contact.xhtml:
<h:head/>
 <h:body> 
  <p:commandButton value="Envoie la sauce" action="#{mail.sendEmail()}"  >
   <f:ajax execute="@form" render="@form" />
  </p:commandButton>
</h:body>
It refers to the following bean action:
@ManagedBean(name="mail")
@SessionScoped
public class MailBean {
public void sendEmail() throws IOException {
    Properties props = new Properties();
    props.put("mail.smtp.host", "smtp.gmail.com");
    props.put("mail.smtp.socketFactory.port", "465");
    props.put("mail.smtp.socketFactory.class",
            "javax.net.ssl.SSLSocketFactory");
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.port", "465");
    Session session = Session.getDefaultInstance(props,
        new javax.mail.Authenticator() {
                            @Override
    protected PasswordAuthentication getPasswordAuthentication() {
    return new PasswordAuthentication("username","password");
            }
        });
    try {
        Message message = new MimeMessage(session);
        message.setFrom(new InternetAddress("toto@yopmail.com"));
        message.setRecipients(Message.RecipientType.TO,
                InternetAddress.parse("toto@gmail.com"));
        message.setSubject("Demande de Contact");
        message.setText("Dear Mail Crawler," +
                "\n\n No spam to my email, please!");
        Transport.send(message);
                    //to see if message was send
        System.out.println("Done");
    } catch (MessagingException e) {
        throw new RuntimeException(e);
    }
}
}
This is supposed to send a mail via JavaMail, however the button doesn't do anything except refreshing the page.
I have tested the SendHTMLEmail class as a stand alone Java Application, it works perfectly.
What i'm trying to do is a simple contact form made in xhtml using JSF2.1.
UPDATE-
Ok some news today !
If i use this thing : <p:commandButton action="#{mail.send()}"/> on the page index.xhtml something happen i have to determine why the class can't be find... : 
<?xml version='1.0' encoding='UTF-8'?>
<partial-response><error><error-name>class javax.faces.el.EvaluationException</error-name><error-message><![CDATA[/index.xhtml @35,47 action="#{mail.send()}": Target Unreachable, identifier 'mail' resolved to null]]></error-message></error></partial-response>
BUT on the contact.xhtml i have only this with the same button :
<?xml version='1.0' encoding='UTF-8'?>
<partial-response><changes><update id="log:messages"><![CDATA[<div id="log:messages" class="ui-messages ui-widget" aria-live="polite"></div>]]></update><update id="javax.faces.ViewState"><![CDATA[-2283025416922274948:-229809047557820449]]></update></changes></partial-response>
So all my have an unique id ! Someone have an idea to what happen ? edit1 : full code added edit2 : added the index.html with all balises edit3 : Discovered something about the action button into my xhtml page