diff --git a/master.cfg b/master.cfg
index 782652a..83f160b 100644
--- a/master.cfg
+++ b/master.cfg
@@ -377,7 +377,7 @@ mn = mail.MailNotifier(fromaddr = GDB_MAIL_FROM,
                        mode = ('failing'),
                        messageFormatter = MessageGDBTesters,
                        extraHeaders = { 'X-GDB-Buildbot' : '1',
-                                        'In-Reply-To' : WithProperties ("<%s@" + socket.gethostname () + ">",
+                                        'In-Reply-To' : WithProperties ("<%s@gdb-build>",
                                                                         'got_revision') })
 
 c['status'].append (mn)