<?php

function mynews_menu() {
  $items['newsletter'] = array(
    'title' => 'Newsletter registration page',
    'page callback' => '_mynews_newsletter_registration_page',
    'page arguments' => array(1),
    'access callback' => TRUE,
  );

  return $items;
}

function _mynews_newsletter_registration_page() {
// NOTE: on the second loading on this page,
// the $_POST variable is empty.
// This happens only when the block is called from
// the 'newsletter' page.
dpm($_POST);
dpm($_POST['mail']);
  $retval = "";
  $retval .= "<pre>";
  $retval .= print_r($_POST['mail'], TRUE);
  $retval .= "</pre>";
  return $retval;
}

function mynews_block_info() {
  $blocks['mynews'] = array(
    'info' => t('My news'),
  );

  return $blocks;
}

function mynews_block_view($delta = '') {
  $block = array();
  // The $delta parameter tells us which block is being requested.
  switch ($delta) {
    case 'mynews':
      $block['subject'] = t('My news');
      $block['content'] = drupal_get_form('mynews_form');
      break;
  }
  return $block;
}

function mynews_form() {
  $form['#action'] = 'newsletter';

  $form['mail'] = array(
    '#type'           => 'textfield',
    '#maxlength'      => 255,
    '#size'           => 25,
    '#element_validate' => array('mynews_email_validate'),
    '#attributes'     => array('class' => array('edit-mail')),
  );

  $form['submit'] = array(
    '#type'  => 'submit',
    '#value' => 'Subscribe',
  );

  return $form;
}

function mynews_email_validate($element, &$form_state, $form) {
  if (empty($element['#value']) || !valid_email_address($element['#value'])) {
    form_set_error($element['#name'],
      t("Invalid e-mail address '@submitted_email'. Please verify your syntax.",
        array('@submitted_email' => check_plain($element['#value'])))
    );
  }
}