--- a/roundup/mailer.py
+++ b/roundup/mailer.py
@@ -6,6 +6,7 @@
 import os
 import smtplib
 import socket
+import ssl
 import sys
 import time
 import traceback
@@ -312,8 +313,11 @@
         # start the TLS if requested
         if config["MAIL_TLS"]:
             self.ehlo()
-            self.starttls(config["MAIL_TLS_KEYFILE"],
-                          config["MAIL_TLS_CERTFILE"])
+            sslctx = ssl.SSLContext()
+            if config["MAIL_TLS_CERTFILE"]:
+                load_cert_chain(config["MAIL_TLS_CERTFILE"],
+                                keyfile=config["MAIL_TLS_KEYFILE"])
+            self.starttls(context=sslctx)

         # ok, now do we also need to log in?
         mailuser = config["MAIL_USERNAME"]