You can configure mail service by editing mail-service.xml file in your deploy directory.

Sample code:

import javax.mail.Transport;
import javax.mail.Session;
import javax.ejb.SessionContext;

@Stateless
public class SessionBean implements ISessionBeanLocal{
 @Resource(mappedName="java:/Mail")
 private Session mailSession;

 @Resource
 private SessionContext ctx;

 public void sendAMessage(){
 MimeMessage m = new MimeMessage(session);
 m.setFrom(fromAddress);
 ............
 Transport.send(m)
 }

 public void legacySend(){
 Session mailSession = (Session)PortableRemoteObject.narrow(
 ctx.lookup("java:/Mail"), Session.class);
 MimeMessage m = new MimeMessage(session);
 m.setFrom(fromAddress);
 ............
 Transport.send(m)
 }
}