code: @Override
      protected void initializeImpl()
      {
          //create properties from configuration (all javax mail properties will be defined in the fax4j properties)
          this.mailConnectionProperties=new Properties();
          Map<String,String> configuration=this.factoryConfigurationHolder.getConfiguration();
          Iterator<Entry<String,String>> iterator=configuration.entrySet().iterator();
          Entry<String,String> entry=null;
          String key=null;
          String value=null;
          while(iterator.hasNext())
          {
              //get next entry
              entry=iterator.next();
  
              //get next key
              key=entry.getKey();
              if((key!=null)&&(key.indexOf("org.fax4j.")==-1))    //filter out fax4j properties
              {
                  //get next value
                  value=entry.getValue();
                  
                  //put in properties
                  this.mailConnectionProperties.setProperty(key,value);
              }
          }
          
          //get user/password values
          this.userName=this.factoryConfigurationHolder.getConfigurationValue(FaxClientSpiConfigurationConstants.USER_NAME_PROPERTY_KEY);
          this.password=this.factoryConfigurationHolder.getConfigurationValue(FaxClientSpiConfigurationConstants.PASSWORD_PROPERTY_KEY);
  
          //get transport protocol
          this.transportProtocol=this.factoryConfigurationHolder.getConfigurationValue("mail.transport.protocol");
          if(this.transportProtocol==null)
          {
              this.transportProtocol="smtp";
          }
  
          //get transport host
          this.transportHost=this.factoryConfigurationHolder.getConfigurationValue("mail.smtp.host");
          
          //get transport port
          String transportPortStr=this.factoryConfigurationHolder.getConfigurationValue("mail.smtp.port");
          this.transportPort=-1;
          if(transportPortStr!=null)
          {
              this.transportPort=Integer.parseInt(transportPortStr);
          }
      }
docs: This function initializes the connection factory.