diff --git a/master.cfg b/master.cfg
index c93d4a3..782652a 100644
--- a/master.cfg
+++ b/master.cfg
@@ -170,7 +170,7 @@ def SendRootMessageGDBTesters (branch, change):
     mail['Subject'] = sbj
     mail['From'] = GDB_MAIL_FROM
     mail['To'] = GDB_MAIL_TO
-    mail['Message-Id'] = "<%s@%s>" % (rev, socket.gethostname ())
+    mail['Message-Id'] = "<%s@gdb-build>" % rev
 
     s = smtplib.SMTP ('localhost')
     s.sendmail (GDB_MAIL_FROM, [ GDB_MAIL_TO ], mail.as_string ())