Provides an Administrative UI and Developers API for safely updating the mail_system configuration variable.

The 6.x-1.x branch also provides a Drupal-6 backport of the Drupal-7 mail system. For more information, see Creating HTML formatted emails in Drupal 7.

Administrative UI

The administrative interface is at admin/config/system/mailsystem. A screenshot is available.

Used by;

• HTML Mail
• Postmark

Developers API

A module example with a MailSystemInterface implementation called ExampleMailSystem should add the following in its example.install file:

/**
 * Implements hook_enable().
 */
function example_enable() {
  mailsystem_set(array('example' => 'ExampleMailSystem'));
}
/**
 * Implements hook_disable().
 */
function example_disable() {
  mailsystem_clear(array('example' => 'ExampleMailSystem'));
}

The above settings allow mail sent by example to use ExampleMailSystem. To make ExampleMailSystem the site-wide default for sending mail:

mailsystem_set(array(mailsystem_default_id() => 'ExampleMailSystem'));

To restore the default mail system:

mailsystem_set(array(mailsystem_default_id() => mailsystem_default_value()));

Or simply:

mailsystem_set(mailsystem_defaults());

If module example relies on dependency foo and its FooMailSystem class, then the example.install code should like like this:

/**
 * Implements hook_enable().
 */
function example_enable() {
  mailsystem_set(array('example' => 'FooMailSystem'));
}
/**
 * Implements hook_disable().
 */
function example_disable() {
  mailsystem_clear(array('example' => ''));
}

If module example only wants to use FooMailSystem when sending emails with a key of examail, then the example.install code should look like this:

/**
 * Implements hook_enable().
 */
function example_enable() {
  mailsystem_set(array('example_examail' => 'FooMailSystem'));
}
/**
 * Implements hook_disable().
 */
function example_disable() {
  mailsystem_clear(array('example_examail' => ''));
}

References

drupal_mail_system() API documentation:

http://api.drupal.org/api/drupal/includes--mail.inc/function/drupal_mail_system/7

MailSystemInterface API documentation:

http://api.drupal.org/api/drupal/includes--mail.inc/interface/MailSystemInterface/7

Creating HTML formatted mails in Drupal 7

http://drupal.org/node/900794