Postoffice API: Events and BodyRenderer

Last updated on

30 November 2022

The \Symfony\Component\Mailer\Event\MessageEvent event is dispatched before an e-mail is handed off to the MTA. Postoffice comes with a set of subscribers for this event. Subscribing to the MessageEvent is the principal extension point for contrib and custom code.

When adding subscribers, it is recommended to choose the priority according to their purpose:

Positive priority for subscribers to be run before any BodyRenderer.
Priority 0 for any subscriber invoking a BodyRenderer.
Priority -50 for twig extensions.

Event subscribers for MessageEvent
Module	Priority
Module: Postoffice, Service: `postoffice.body_subscriber` Class: `\Symfony\Component\Mailer\EventListener\MessageListener` Invokes `postoffice.body_renderer` in order to render the body of messages implementing the `\Drupal\postoffice\Email\ThemedEmailInterface`	0
Module: Postoffice File, Service: `postoffice_file.attachment_subscriber` Class: `\Drupal\postoffice_file\EventSubscriber\FileAttachmentSubscriber` Attaches files supplied by the `postoffice_file_attach_uri` and `postoffice_file_attach_entity` twig filters.	-50
Module: Postoffice Image, Service: `postoffice_image.image_embed_subscriber` Class: `\Drupal\postoffice_image\EventSubscriber\ImageEmbedSubscriber` Embeds images supplied by the postoffice_image_embed twig filter.	-50
Module: Postoffice Twig, Service: `postoffice_twig.subject_subscriber` Class: `\Drupal\postoffice_twig\EventSubscriber\TwigSubjectSubscriber` Sets the subject supplied by the `postoffice_subject` twig filter.	-50
Module: Postoffice Twig, Service: `postoffice_twig.text_body_subscriber` Class: `\Drupal\postoffice_twig\EventSubscriber\TwigTextBodySubscriber` Sets the text body supplied by the `postoffice_text_body` twig filter.	-50
Module: Postoffice Html2Text, Service: `postoffice_html2text.message_subscriber` Class: `\Drupal\postoffice_html2text\EventSubscriber\MessageSubscriber` Generates a plain text part for every HTML message.	-100
Module: Postoffice Skel, Service: `postoffice_skel.message_subscriber` Class: `\Drupal\postoffice_skel\EventSubscriber\MessageSubscriber` Wraps a message into a HTML document skeleton.	-125
Module: Postoffice Inline Styles, Service: `postoffice_inline_styles.message_subscriber` Class: `\Drupal\postoffice_inline_styles\EventSubscriber\MessageSubscriber` Inlines CSS from libraries attached during the rendering of a message.	-150
Module: Postoffice, Service: `postoffice.default_address_subscriber` Class: `\Drupal\postoffice\EventSubscriber\DefaultAddressSubscriber` Sets the `sender`, `from` and `to` address to the site default if one of them is still empty.	-200