diff --git a/etc/NEWS b/etc/NEWS
index e09f32a7c35..e97755a4541 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -405,6 +405,8 @@ Previously 'xml-print' would produce invalid XML when given a string
 with characters that are not valid in XML (see
 https://www.w3.org/TR/xml/#charsets).  Now it rejects such strings.
 
+** The metamail.el library is now marked obsolete.
+
 
 * New Modes and Packages in Emacs 28.1
 
diff --git a/lisp/mail/metamail.el b/lisp/obsolete/metamail.el
similarity index 99%
rename from lisp/mail/metamail.el
rename to lisp/obsolete/metamail.el
index 0e407ea060e..d6ab4a3d0cf 100644
--- a/lisp/mail/metamail.el
+++ b/lisp/obsolete/metamail.el
@@ -4,6 +4,7 @@
 
 ;; Author: Masanobu UMEDA <umerin@mse.kyutech.ac.jp>
 ;; Keywords: mail, news, mime, multimedia
+;; Obsolete-since: 28.1
 
 ;; This file is part of GNU Emacs.