WordPress Mail Hools

available-mail-hooks.php

<?php

/**
 * Filter the wp_mail() arguments.
 *
 * @since 2.2.0
 *
 * @param array $args A compacted array of wp_mail() arguments, including the "to" email,
 *                    subject, message, headers, and attachments values.
 */
$atts = apply_filters( 'wp_mail', compact( 'to', 'subject', 'message', 'headers', 'attachments' ) );

/**
 * Filter the email address to send from.
 *
 * @since 2.2.0
 *
 * @param string $from_email Email address to send from.
 */
$phpmailer->From = apply_filters( 'wp_mail_from', $from_email );

/**
 * Filter the name to associate with the "from" email address.
 *
 * @since 2.3.0
 *
 * @param string $from_name Name associated with the "from" email address.
 */
$phpmailer->FromName = apply_filters( 'wp_mail_from_name', $from_name );

/**
 * Filter the wp_mail() content type.
 *
 * @since 2.3.0
 *
 * @param string $content_type Default wp_mail() content type.
 */
$content_type = apply_filters( 'wp_mail_content_type', $content_type );

/**
 * Filter the default wp_mail() charset.
 *
 * @since 2.3.0
 *
 * @param string $charset Default email charset.
 */
$phpmailer->CharSet = apply_filters( 'wp_mail_charset', $charset );

/**
 * Fires after PHPMailer is initialized.
 *
 * @since 2.2.0
 *
 * @param PHPMailer &$phpmailer The PHPMailer instance, passed by reference.
 */
do_action_ref_array( 'phpmailer_init', array( &$phpmailer ) );

debug-hook-function.php

<?php

if ( defined( 'WP_DEBUG') && true == WP_DEBUG ) {

	class MailHooksDebugger {
	
		public static function create() {
			$obj = new self();
			add_filter( 'wp_mail',              array( $obj, 'wp_mail_arguments' ) );
			add_filter( 'wp_mail_from',         array( $obj, 'wp_mail_from' ) );
			add_filter( 'wp_mail_from_name',    array( $obj, 'wp_mail_from_name' ) );
			add_filter( 'wp_mail_content_type', array( $obj, 'wp_mail_content_type' ) );
			add_filter( 'wp_mail_charset',      array( $obj, 'wp_mail_charset' ) );
			add_action( 'phpmailer_init',       array( $obj, 'phpmailer_init' ) );
		}

		protected function error_log( $method, $arg ) {
			$msg = sprintf( "Filter '%s': %s", $method, print_r( $arg, true ) );
			error_log( $msg );
			return $arg;
		}

		function __call( $method, $arg ) {
			return $this->error_log( $method, $arg );
		}

		function phpmailer_init( &$args ) {
			$this->error_log( __METHOD__, $args[0] );
		}

	}
	MailHooksDebugger::create();

}