Perform action when new user verifies email link
I also updated the link your posted to.

If you're using the LoginToboggan module for e-mail validation and you don't wish to use the rules module you can simply mimic the module's validation response (exploiting a temporary logintoboggan_email_validated = TRUE account property that's pushed to hook_user_update) yourself in code:

 /**
 * Implement hook_user_update()
 *
 */
function yourcustommodule_user_update(&amp;$edit, $account) {
  if (!empty($account-&gt;logintoboggan_email_validated) &amp;&amp; !isset($account-&gt;your_custom_action)) {
        $account-&gt;your_custom_action = TRUE;

        // Do what you want here

  }
}


Since core and other modules will also invoke hook_user_update you'd want to implement something to avoid repeated actions. In this example I set another property on the $account once the action is initiated but you can impose finer control if necessary.