Attach a site-wide contact form to a block

attach-contact-form-to-block.php

<?php
 //Open template.php in your theme folder and add the following code. Replace [THEME NAME] with the name of your theme. Replace the value of $module and $delta with the actual string values.

//Hint: To locate these values go to admin/structure/block and click on the "configure" link next to the block you want to print. The strings will be shown in the URL as such: admin/structure/block/manage/[module]/[delta]/configure.
 /**
 * Implements preprocess_block().
 */
function mytheme_preprocess_block(&$vars) {
  // Preprocess the Contact form block. 
  $module = 'block';
  $delta = 3;
  if ($vars['block']->module == $module && $vars['block']->delta == $delta) {
    module_load_include('inc', 'contact', 'contact.pages');
    $contact_form = drupal_get_form('contact_site_form');
    // Manually prepare status messages.
    $contact_form['#prefix'] = theme('status_messages');
    $vars['content'] = render($contact_form);
  }
}