Don't dispatch e-mails related to Temporary Users

changelog/fix-email-guest-users

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fixed
+
+Don't send e-mails to Guest/Preview users

includes/class-sensei-emails.php

@@ -167,16 +167,16 @@ function send( $to, $subject, $message, $headers = "Content-Type: text/html\r\n"
 		add_filter( 'wp_mail_from_name', array( $this, 'get_from_name' ) );
 		add_filter( 'wp_mail_content_type', array( $this, 'get_content_type' ) );
 
-		// Send
-		$send_email = true;
-
 		/**
 		 * Filter Sensei's ability to send out emails.
 		 *
 		 * @since 1.8.0
-		 * @param bool $send_email default true
+		 * @param bool $send_email Whether to send the email or not.
+		 * @param mixed $to The email address(es) to send the email to.
+		 * @param mixed $subject The subject of the email.
+		 * @param mixed $message The message of the email.
 		 */
-		if ( apply_filters( 'sensei_send_emails', $send_email, $to, $subject, $message ) ) {
+		if ( apply_filters( 'sensei_send_emails', true, $to, $subject, $message ) ) {
 
 			wp_mail( $to, $subject, $message, $headers, $attachments );
 

includes/class-sensei-guest-user.php

@@ -40,6 +40,15 @@ class Sensei_Guest_User {
 	 */
 	const LOGIN_PREFIX = 'sensei_guest_';
 
+	/**
+	 * Email domain used for guest users.
+	 *
+	 * @since $$next-version$$
+	 *
+	 * @var string
+	 */
+	const EMAIL_DOMAIN = 'guest.senseilms';
+
 	/**
 	 * Guest user id.
 	 *
@@ -137,7 +146,8 @@ public function init() {
 		add_action( 'sensei_is_enrolled', [ $this, 'open_course_always_enrolled' ], 10, 3 );
 		add_action( 'sensei_can_access_course_content', [ $this, 'open_course_enable_course_access' ], 10, 2 );
 		add_action( 'sensei_can_user_manually_enrol', [ $this, 'open_course_user_can_manualy_enroll' ], 10, 2 );
-		add_action( 'sensei_send_emails', [ $this, 'skip_sensei_email' ] );
+		add_filter( 'sensei_send_emails', [ $this, 'skip_sensei_email' ] );
+		add_filter( 'pre_wp_mail', [ $this, 'skip_wp_mail' ], 10, 2 );
 
 		$this->create_guest_student_role_if_not_exists();
 
@@ -327,7 +337,7 @@ public static function create_guest_user() {
 			[
 				'user_pass'    => wp_generate_password(),
 				'user_login'   => $user_name,
-				'user_email'   => $user_name . '@guest.senseilms',
+				'user_email'   => $user_name . '@' . self::EMAIL_DOMAIN,
 				'display_name' => 'Guest Student ' . str_pad( $user_count, 3, '0', STR_PAD_LEFT ),
 				'role'         => self::ROLE,
 			]
@@ -466,7 +476,28 @@ private function is_action( $field, $nonce ) {
 	 */
 	public function skip_sensei_email( $send_email ) {
 		return $this->is_current_user_guest() ? false : $send_email;
+	}
 
+	/**
+	 * Prevent emails related to the guest user from being dispatched via wp_mail.
+	 *
+	 * @access private
+	 * @since  $$next-version$$
+	 *
+	 * @param bool|null $return Null if we should send the email, a boolean if not.
+	 * @param array     $atts   Email attributes.
+	 * @return bool|null Null if we should send the email, a boolean if not.
+	 */
+	public function skip_wp_mail( $return, $atts ) {
+		if ( $this->is_current_user_guest() ) {
+			// If this e-mail is being dispatched while the current user is a guest, just... don't send it.
+			return false;
+		}
+		if ( Sensei_Temporary_User::should_block_email( $atts, self::EMAIL_DOMAIN ) ) {
+			// If this e-mail is being dispatched to a guest user, don't send it.
+			return false;
+		}
+		return $return;
 	}
 
 	/**

includes/class-sensei-preview-user.php

@@ -29,6 +29,15 @@ class Sensei_Preview_User {
 	const SWITCH_ON_ACTION  = 'sensei-preview-as-student';
 	const SWITCH_OFF_ACTION = 'sensei-exit-student-preview';
 
+	/**
+	 * Email domain used for preview users.
+	 *
+	 * @since $$next-version$$
+	 *
+	 * @var string
+	 */
+	const EMAIL_DOMAIN = 'preview.senseilms';
+
 	/**
 	 * Meta key for the associated preview user ID.
 	 * Used to link the original teacher and the preview user, in both directions.
@@ -83,6 +92,7 @@ public function init() {
 		add_action( 'show_admin_bar', [ $this, 'show_admin_bar_to_preview_user' ], 90 );
 		add_action( 'admin_bar_menu', [ $this, 'add_user_switch_to_admin_bar' ], 90 );
 		add_filter( 'sensei_is_enrolled', [ $this, 'preview_user_always_enrolled' ], 90, 3 );
+		add_filter( 'pre_wp_mail', [ $this, 'skip_wp_mail' ], 10, 2 );
 
 		$this->create_role();
 	}
@@ -97,7 +107,7 @@ public function add_preview_user_filters() {
 			add_filter( 'map_meta_cap', [ $this, 'allow_post_preview' ], 10, 4 );
 			add_filter( 'pre_get_posts', [ $this, 'count_unpublished_lessons' ], 10 );
 			add_filter( 'sensei_notice', [ $this, 'hide_notices' ], 10, 1 );
-			add_action( 'sensei_send_emails', '__return_false' );
+			add_filter( 'sensei_send_emails', '__return_false' );
 
 		}
 
@@ -244,6 +254,28 @@ private function can_switch_to_preview_user( $course_id ) {
 		return Sensei_Course::can_current_user_edit_course( $course_id );
 	}
 
+	/**
+	 * Prevent emails related to the preview user from being dispatched via wp_mail.
+	 *
+	 * @access private
+	 * @since  $$next-version$$
+	 *
+	 * @param bool|null $return Null if we should send the email, a boolean if not.
+	 * @param array     $atts   Email attributes.
+	 * @return bool|null Null if we should send the email, a boolean if not.
+	 */
+	public function skip_wp_mail( $return, $atts ) {
+		if ( $this->is_preview_user_active() ) {
+			// If this e-mail is being dispatched while the current user is a previwe user, just... don't send it.
+			return false;
+		}
+		if ( Sensei_Temporary_User::should_block_email( $atts, self::EMAIL_DOMAIN ) ) {
+			// If this e-mail is being dispatched to a preview user, don't send it.
+			return false;
+		}
+		return $return;
+	}
+
 	/**
 	 * Check if the request is for the given action.
 	 *
@@ -272,7 +304,7 @@ private function create_preview_user( $course_id ) {
 			[
 				'user_pass'    => wp_generate_password(),
 				'user_login'   => $user_name,
-				'user_email'   => $user_name . '@preview.senseilms',
+				'user_email'   => $user_name . '@' . self::EMAIL_DOMAIN,
 				'display_name' => $display_name,
 				'last_name'    => $display_name,
 				'role'         => self::ROLE,

includes/class-sensei-temporary-user.php

@@ -120,6 +120,59 @@ public static function filter_learners_query( string $query ) {
 		);
 	}
 
+	/**
+	 * Detect if the e-mail attributes relate to an e-mail from a temporary user.
+	 *
+	 * @access private
+	 * @since  $$next-version$$
+	 *
+	 * @param array  $atts   Email attributes.
+	 * @param string $email_domain The email domain to search for.
+	 * @return boolean Whether to block the email or not.
+	 */
+	public static function should_block_email( $atts, $email_domain ) {
+		$emails = $atts['to'];
+		if ( ! is_array( $emails ) ) {
+			$emails = explode( ',', $emails );
+		}
+		if ( ! empty( $atts['headers'] ) ) {
+			$headers = $atts['headers'];
+			if ( ! is_array( $headers ) ) {
+				// Explode the headers out, so this function can take
+				// both string headers and an array of headers.
+				$temp_headers = explode( "\n", str_replace( "\r\n", "\n", $headers ) );
+			} else {
+				$temp_headers = $headers;
+			}
+			// If it's actually got contents.
+			if ( ! empty( $temp_headers ) ) {
+				foreach ( $temp_headers as $name => $content ) {
+					if ( is_int( $name ) && str_contains( $content, ':' ) ) {
+						list ( $name, $content) = explode( ':', trim( $content ), 2 );
+					}
+
+					// Cleanup crew.
+					$name    = trim( $name );
+					$content = trim( $content );
+
+					if ( in_array( strtolower( $name ), [ 'from', 'cc', 'bcc', 'reply-to' ], true ) ) {
+						$emails = array_merge( (array) $emails, explode( ',', $content ) );
+					}
+				}
+			}
+		}
+		foreach ( $emails as $address ) {
+			if ( preg_match( '/(.*)<(.+)>/', $address, $matches ) && count( $matches ) === 3 ) {
+				$address = $matches[2];
+			}
+			if ( str_ends_with( $address, '@' . $email_domain ) ) {
+				// If this is an e-mail address for a guest user, don't send it.
+				return true;
+			}
+		}
+		return false;
+	}
+
 	/**
 	 * Make sure temporary users are not counted.
 	 * When the user has an ungraded quiz, they are still counted, since they will show up in the grading list, as per self::filter_sensei_activity.

includes/internal/emails/class-email-sender.php

@@ -116,14 +116,22 @@ public function send_email( $email_name, $replacements, $usage_tracking_type ) {
 		$replacements = apply_filters( 'sensei_email_replacements', $replacements, $email_name, $email_post, $this );
 
 		foreach ( $replacements as $recipient => $replacement ) {
-			wp_mail(
-				$recipient,
-				$this->get_email_subject( $email_post, $replacement ),
-				$this->get_email_body( $email_post, $replacement ),
-				$this->get_email_headers(),
-				null
-			);
-			sensei_log_event( 'email_send', [ 'type' => $usage_tracking_type ] );
+			$subject = $this->get_email_subject( $email_post, $replacement );
+			$message = $this->get_email_body( $email_post, $replacement );
+
+			/*
+			 * For documentation of the filter check class-sensei-emails.php file.
+			 */
+			if ( apply_filters( 'sensei_send_emails', true, $recipient, $subject, $message ) ) {
+				wp_mail(
+					$recipient,
+					$subject,
+					$message,
+					$this->get_email_headers(),
+					null
+				);
+				sensei_log_event( 'email_send', [ 'type' => $usage_tracking_type ] );
+			}
 		}
 	}