function validate_mail(form) {
	  
  var email_from = form.email_from;
  var email_address = form.email_address;
  var email_subject = form.email_subject;
  var email_content = form.email_content;
  
  var email_from_correct = false;
  var email_address_correct = false;
  var email_subject_correct = false;
  var email_content_correct = false;
  
  var warning_color = "#ea4f3c";
  var correct_color = "#ffffff";
	
	if ( email_from.value == "" || email_from.value == null ) {
	
		email_from_correct = false;
		
		email_from.style.background = warning_color;
		
	} else {
	
		email_from_correct = true;
		
		email_from.style.background = correct_color;

	}
	
	if ( email_address.value == "" || email_address.value == null ) {
	
		email_address_correct = false;
		
		email_address.style.background = warning_color;

	} else {
	
		email_address_correct = true;
		
		email_address.style.background = correct_color;

	}
	
	if ( email_subject.value == "" || email_subject.value == null ) {
	
		email_subject_correct = false;
		
		email_subject.style.background = warning_color;

	} else {
	
		email_subject_correct = true;
		
		email_subject.style.background = correct_color;

	}
	
	if ( email_content.value == "" || email_content.value == null ) {
	
		email_content_correct = false;
		
		email_content.style.background = warning_color;

	} else {
	
		email_content_correct = true;
		
		email_content.style.background = correct_color;

	}

	if ( email_from_correct && email_address_correct && email_subject_correct && email_content_correct ) {

		return true;
		
	} else {
	
    if ( document.getElementById('email_message_php') ) {
	
      document.getElementById('email_message_php').style.display = "none";
      
    }
    
    document.getElementById('email_message_js').style.display = "block";
    document.getElementById('email_message_js').innerHTML = "Prosím vyplňte všetky povinné položky";

		return false;
	  
  }
  
}