I have a wordpress site that have plugins: Contact form 7, WP Mail SMTP Plugin by Mail Bank, Spartpost...All of these plugins are able to send out email by anyway (wp_mail, smtp, http api)...
I am developing another plugin that will do my custom action on each sent out email by any plugin.
Currently, I can do the custom action on contact form 7 email with:
add_action('wpcf7_before_send_mail', 'my_custom_action', 10, 1);
My question: is there any hook, filter or something that is general to wordpress email? Instead of use action/filter of every plugins?