Drupal 7 Module Development

Chapter 5
• The second argument, warn, is a key which is passed to hook_mail(). Any
hook_mail() implementation can define several e-mails, uniquely identified
by a text key. (Drupal's user module implements eighteen (!) for things like
account confirmation and forgotten passwords). We specify which specific
mail we want to send with this parameter.
• The third argument contains the recipient's address. We pull this out of
the user object for the user whose profile we visited, as passed by the
confirmation form above.
• The fourth argument specifies what language the mail should be sent in. This
is important because individual users can specify a language preference that
is different from the site's default language. We should honor this choice
if possible when sending our e-mail to this user. The user_preferred_
language() function makes this task easy by taking a user object and
returning the user's language choice.
• The fifth argument is an associative array of parameters to be passed to
hook_mail(). Any custom information needed to build the e-mail should be
put here. In our case, any custom information we need to build the e-mail is
already in the data submitted from the confirmation form, so we will just use
$form_state['values'] here.
• The sixth argument contains the e-mail address from whom this mail should
be sent. When you first installed Drupal you had to specify an administrative
e-mail address. This address is already being used as the source for other
system e-mails (like account verification) so it makes sense to use it as our
sender e-mail as well. The e-mail is stored as a persistent variable with
the key 'site_mail', so we can easily grab it using variable_get() as
discussed earlier in the chapter.
• Finally, the last variable indicates whether or not the mail should actually be
sent. It will come as no surprise to learn that a mail message in Drupal is built
in a specially structured associative array. At the end of the mail building
process, this array is typically passed to the function drupal_mail_send()
which handles the actual delivery of the mail. However, by setting this
parameter to FALSE, drupal_mail() will bypass the delivery step, allowing
you to take the structured array it returns and handle delivery yourself.
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