Change "From" element in drupal mail
We can easily change the From with hook_mail_alter using 'from'
key from $message.

function mymodule_mail_alter(&amp;$message) { 
  $message['from'] = 'Your Name ('. $message['from'] . ')'; 
}


Also, Please check hook_mail function https://api.drupal.org/api/drupal/modules%21system%21system.api.php/function/hook_mail/7 which needs to be written for your module and then you need to call drupal_mail function.

hook_mail_alter is just for modifying the variables passed to drupal_mail.