diff -r 3d4e9c994f10 -r a86126ab1dd4 wp/wp-mail.php
--- a/wp/wp-mail.php	Tue Oct 22 16:11:46 2019 +0200
+++ b/wp/wp-mail.php	Tue Dec 15 13:49:49 2020 +0100
@@ -8,7 +8,7 @@
  */
 
 /** Make sure that the WordPress bootstrap has run before continuing. */
-require( dirname( __FILE__ ) . '/wp-load.php' );
+require __DIR__ . '/wp-load.php';
 
 /** This filter is documented in wp-admin/options.php */
 if ( ! apply_filters( 'enable_post_by_email_configuration', true ) ) {
@@ -26,14 +26,14 @@
  *
  * @since 2.9.0
  */
-do_action( 'wp-mail.php' );
+do_action( 'wp-mail.php' ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores
 
 /** Get the POP3 class with which to access the mailbox. */
-require_once( ABSPATH . WPINC . '/class-pop3.php' );
+require_once ABSPATH . WPINC . '/class-pop3.php';
 
 /** Only check at this interval for new messages. */
 if ( ! defined( 'WP_MAIL_INTERVAL' ) ) {
-	define( 'WP_MAIL_INTERVAL', 300 ); // 5 minutes
+	define( 'WP_MAIL_INTERVAL', 5 * MINUTE_IN_SECONDS );
 }
 
 $last_checked = get_transient( 'mailserver_last_checked' );
@@ -101,7 +101,7 @@
 				$content_transfer_encoding = explode( ';', $content_transfer_encoding );
 				$content_transfer_encoding = $content_transfer_encoding[0];
 			}
-			if ( ( $content_type == 'multipart/alternative' ) && ( false !== strpos( $line, 'boundary="' ) ) && ( '' == $boundary ) ) {
+			if ( ( 'multipart/alternative' === $content_type ) && ( false !== strpos( $line, 'boundary="' ) ) && ( '' === $boundary ) ) {
 				$boundary = trim( $line );
 				$boundary = explode( '"', $boundary );
 				$boundary = $boundary[1];
@@ -109,7 +109,7 @@
 			if ( preg_match( '/Subject: /i', $line ) ) {
 				$subject = trim( $line );
 				$subject = substr( $subject, 9, strlen( $subject ) - 9 );
-				// Captures any text in the subject before $phone_delim as the subject
+				// Captures any text in the subject before $phone_delim as the subject.
 				if ( function_exists( 'iconv_mime_decode' ) ) {
 					$subject = iconv_mime_decode( $subject, 2, get_option( 'blog_charset' ) );
 				} else {
@@ -131,7 +131,7 @@
 				}
 				$author = sanitize_email( $author );
 				if ( is_email( $author ) ) {
-					/* translators: Post author email address */
+					/* translators: %s: Post author email address. */
 					echo '<p>' . sprintf( __( 'Author is %s' ), $author ) . '</p>';
 					$userdata = get_user_by( 'email', $author );
 					if ( ! empty( $userdata ) ) {
@@ -141,17 +141,18 @@
 				}
 			}
 
-			if ( preg_match( '/Date: /i', $line ) ) { // of the form '20 Mar 2002 20:32:37 +0100'
-				$ddate         = str_replace( 'Date: ', '', trim( $line ) );
-				$ddate         = preg_replace( '!\s*\(.+\)\s*$!', '', $ddate ); // remove parenthesised timezone string if it exists, as this confuses strtotime
-				$ddate_U       = strtotime( $ddate );
-				$post_date     = gmdate( 'Y-m-d H:i:s', $ddate_U + $time_difference );
-				$post_date_gmt = gmdate( 'Y-m-d H:i:s', $ddate_U );
+			if ( preg_match( '/Date: /i', $line ) ) { // Of the form '20 Mar 2002 20:32:37 +0100'.
+				$ddate = str_replace( 'Date: ', '', trim( $line ) );
+				// Remove parenthesised timezone string if it exists, as this confuses strtotime().
+				$ddate           = preg_replace( '!\s*\(.+\)\s*$!', '', $ddate );
+				$ddate_timestamp = strtotime( $ddate );
+				$post_date       = gmdate( 'Y-m-d H:i:s', $ddate_timestamp + $time_difference );
+				$post_date_gmt   = gmdate( 'Y-m-d H:i:s', $ddate_timestamp );
 			}
 		}
 	}
 
-	// Set $post_status based on $author_found and on author's publish_posts capability
+	// Set $post_status based on $author_found and on author's publish_posts capability.
 	if ( $author_found ) {
 		$user        = new WP_User( $post_author );
 		$post_status = ( $user->has_cap( 'publish_posts' ) ) ? 'publish' : 'pending';
@@ -162,7 +163,7 @@
 
 	$subject = trim( $subject );
 
-	if ( $content_type == 'multipart/alternative' ) {
+	if ( 'multipart/alternative' === $content_type ) {
 		$content = explode( '--' . $boundary, $content );
 		$content = $content[2];
 
@@ -195,7 +196,7 @@
 		$content = iconv( $charset, get_option( 'blog_charset' ), $content );
 	}
 
-	// Captures any text in the body after $phone_delim as the body
+	// Captures any text in the body after $phone_delim as the body.
 	$content = explode( $phone_delim, $content );
 	$content = empty( $content[1] ) ? $content[0] : $content[1];
 
@@ -212,7 +213,7 @@
 
 	$post_title = xmlrpc_getposttitle( $content );
 
-	if ( $post_title == '' ) {
+	if ( '' === trim( $post_title ) ) {
 		$post_title = $subject;
 	}
 
@@ -245,7 +246,7 @@
 
 	if ( ! $pop3->delete( $i ) ) {
 		echo '<p>' . sprintf(
-			/* translators: %s: POP3 error */
+			/* translators: %s: POP3 error. */
 			__( 'Oops: %s' ),
 			esc_html( $pop3->ERROR )
 		) . '</p>';
@@ -253,7 +254,7 @@
 		exit;
 	} else {
 		echo '<p>' . sprintf(
-			/* translators: %s: the message ID */
+			/* translators: %s: The message ID. */
 			__( 'Mission complete. Message %s deleted.' ),
 			'<strong>' . $i . '</strong>'
 		) . '</p>';