commit 686bd0550797d0ec6225267914cef5cb0e5a61f6
Author: Peter Münster <pm@a16n.net>
Date:   Thu Nov 25 14:25:18 2021 +0100

    Fix spelling of subject line
    
    * lisp/textmodes/ispell.el (ispell-message): Only subjects starting with
    "Re: " are real replies.

diff --git a/lisp/textmodes/ispell.el b/lisp/textmodes/ispell.el
index 4087f7e5f2..ce8a82cda7 100644
--- a/lisp/textmodes/ispell.el
+++ b/lisp/textmodes/ispell.el
@@ -3977,7 +3977,7 @@ ispell-message
 	    (if (re-search-forward "^Subject: *" end-of-headers t)
 		(progn
 		  (goto-char (match-end 0))
-		  (if (and (not (looking-at ".*Re\\>"))
+		  (if (and (not (looking-at "Re: "))
 			   (not (looking-at "\\[")))
 		      (progn
 			(setq case-fold-search old-case-fold-search)