Drupal 7 function to send simple email to developer or administrator.

_custom_simple_mail.php

<?php
/**
 * Sends a simple email.
 * [or] Tested on 2012-05-31 using Drupal 7.12
 *
 * Usage:
 * 1) Paste all the below code into your module or include
 * 2) Configure the two @FIXME's.
 * 3) Visit /_custom_simple_mail to get an email.
 *
 * Credits:
 * @see http://api.drupal.org/api/drupal/includes%21mail.inc/function/drupal_mail_system/7#comment-17489
 * @see http://www.midwesternmac.com/blogs/jeff-geerling/wrapper-function-simple
 *
 */

/**
 * Send a simple email to specified recipient.
 *
 * @param string $message_subject
 * @param string $message_body
 */
function _custom_simple_mail($message_subject, $message_body) {
  // @FIXME Set this value to your email address.
  $my_email = 'myname@gmail.com';
  
  // These value can remain empty.
  $my_module = '';
  $my_mail_token = '';
  
  $from = variable_get('system_mail', $my_email);
  $message = array(
    'id' => $my_module . '_' . $my_mail_token,
    'to' => $my_email,
    'subject' => $message_subject,
    'body' => array($message_body),
    'headers' => array(
      'From' => $from,
      'Sender' => $from,
      'Return-Path' => $from,
    ),
  );
  $system = drupal_mail_system($my_module, $my_mail_token);

  // The format function must be called before calling the mail function. 
  $message = $system->format($message);

  if ($system->mail($message)) {
    drupal_set_message('_custom_simple_mail SUCCESS');
  }
  else {
    drupal_set_message('_custom_simple_mail FAILURE');
  }
}

/**
 * Implements HOOK_init to test _custom_simple_mail.
 *
 * @FIXME Change 'mymodule' to your actual enabled custom module's machine name.
 */
function mymodule_init() {
  if (arg(0) == '_custom_simple_mail' ) {
    drupal_set_message('Testing _custom_simple_mail()...');
    if (function_exists('_custom_simple_mail')) {
      _custom_simple_mail('Test message subject', 'Test message body');
    } else {
      drupal_set_message('<strong>Oops!</strong> Function _custom_simple_mail() was not found.', 'error');
    }
  }
}