How to use a drupal_mail function.

Let's say you want to send mail using drupal_mail function in your "test" custom module (test is an example name of module used below) after the form is submitted. You have to build two functions. First is a test_form_submit function, the second one is the test_mail function.

In the submit function you have to put the code below:

<?php

function test_form_submit($form, &$form_state) {

$to = "test@example.com"; // to e-mail address
$from = "test@example.com"; // from e-mail address

$subject = "text to display in e-mail subject"; // subject of e-mail
$body = "text to display in e-mail body"; //it might be any variable from the form eg. $form_state['values']['your_field']


//params is the array passed to hook_mail function 
$params = array(
    'subject' => $subject,
    'body' => $body,
    );

drupal_mail('test', 'information', $to, language_default(), $params, $from);
 
}

?>

The second function is a test_mail function:

<?php

function test_mail($key, &$message, $params) {
  switch ($key) {
    case 'information':
      $message['subject'] = $params['subject'];
      $message['body'] = $params['body'];
    break;
    }
}

?>

And that's it! Hope you'll find it useful :)