diff --git a/contrib/smtp/smtp-source.py b/contrib/smtp/smtp-source.py
index 9e6b7391..056acc03 100755
--- a/contrib/smtp/smtp-source.py
+++ b/contrib/smtp/smtp-source.py
@@ -100,9 +100,14 @@ parser.add_argument("-s", "--server", type=str, help="smtp server", required=Tru
 parser.add_argument("-p", "--port", type=int, help="smtp port", default=25)
 parser.add_argument("--subject", type=str, help="subject", default="This is test subject")
 parser.add_argument("-l", "--msglen", type=int, help="message length (approx.)", default=20000)
+parser.add_argument("--starttls", help="use STARTTLS", action="store_true")
+parser.add_argument("--pem", type=str, help="pem file for starttls", default="")
 
 args = parser.parse_args()
 
+if args.starttls and args.pem == "":
+    sys.exit("make a pem file for starttls, and add --pem <pem file>")
+
 
 with open(dictionary) as f:
     words = f.readlines()
@@ -111,6 +116,9 @@ i = 0
 while i < args.count:
     server = smtplib.SMTP(args.server, args.port, args.helo, 10)
 
+    if args.starttls:
+        server.starttls(args.pem, args.pem)
+
     k = 0
 
     while i < args.count and k < args.session: