Drupal 7 Module Development

Chapter 5
As discussed earlier, it is possible for hook_mail() to handle multiple different
e-mails as indicated by the key passed in from drupal_mail(). Even though we
are only sending one e-mail with a key of 'warn', we still put it into a switch/case
structure to make it easier to manage more mails later on if needed.
Now we can get on with the real purpose of our hook implementation—adding
details to the $message array that are unique to our mail. Typically this is the subject,
body, and any additional headers that we might need.
Our e-mail's subject and text have been set via the module's configuration page, so
we retrieve them via variable_get() and set them to the $message['subject']
and $message['body] properties here.
Note that we do not pass the subject and body strings through t() as
we have done in other contexts. These strings are supplied by the site
administrator through the User Warn module's configuration form, and
as such are not translatable. Only hardcoded system strings need to be
passed through t().
The other thing we need to do is to Bcc the site admin if that configuration setting
has been set.
if (variable_get('user_warn_bcc', FALSE)) {
$admin_mail = variable_get('site_mail', NULL);
$message['headers']['bcc'] = $admin_mail;
}
As with the other configuration settings, we retrieve it using variable_get(). If it is
TRUE, then we need to set the site admin to be Bcc'd. Unlike the e-mail recipient, Cc
and Bcc are set by adding headers to the $message array. The headers are themselves
an associative array held under the 'headers' key, and we need to add a new
header with the key 'Bcc'. We assign this to the site admin's e-mail in the same
manner as we did in drupal_mail() while setting the mail's sender.
This is all we need to do! $message is passed by reference, so we don't even need to
return it. Drupal will just proceed on from here. After other modules get a chance
to alter the mail through hook_mail_alter(), the $message array will be passed
to drupal_mail_system() where the final mail message will be formatted and
delivered (if you specified this option when you called drupal_mail()).
[ 145 ]