Index: wp-admin/includes/misc.php
===================================================================
--- wp-admin/includes/misc.php	(revision 56010)
+++ wp-admin/includes/misc.php	(working copy)
@@ -1531,16 +1531,19 @@
 		$site_title = parse_url( home_url(), PHP_URL_HOST );
 	}

-	wp_mail(
-		$value,
-		sprintf(
-			/* translators: New admin email address notification email subject. %s: Site title. */
-			__( '[%s] New Admin Email Address' ),
-			$site_title
-		),
-		$content
-	);
+    $subject = sprintf(
+    /* translators: New admin email address notification email subject. %s: Site title. */
+        __( '[%s] New Admin Email Address' ),
+        $site_title
+    );
+    $subject = apply_filters( 'new_admin_email_subject', $subject );

+    wp_mail(
+        $value,
+        $subject,
+        $content
+    );
+
 	if ( $switched_locale ) {
 		restore_previous_locale();
 	}