diff --git a/config.inc.php b/config.inc.php
index d1e76e18..98b00bfa 100644
--- a/config.inc.php
+++ b/config.inc.php
@@ -171,6 +171,9 @@ $CONF['smtp_port'] = '25';
 // Used in the HELO when sending emails from Postfix Admin
 $CONF['smtp_client'] = '';
 
+// Set 'YES' to use TLS when sending emails.
+$CONF['smtp_sendmail_tls'] = 'NO';
+
 // Encrypt
 // In what way do you want the passwords to be crypted?
 // md5crypt = internal postfix admin md5
diff --git a/functions.inc.php b/functions.inc.php
index 42d1d3e6..b6717267 100644
--- a/functions.inc.php
+++ b/functions.inc.php
@@ -1398,12 +1398,15 @@ function smtp_mail($to, $from, $data, $password = "", $body = "") {
         return false;
     } else {
         smtp_get_response($fh);
-        fputs($fh, "STARTTLS\r\n");
-        smtp_get_response($fh);
 
-        stream_set_blocking ($fh, true);
-        stream_socket_enable_crypto($fh, true, STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT);
-        stream_set_blocking ($fh, true);
+        if (Config::read_string('smtp_sendmail_tls') === 'YES') {
+            fputs($fh, "STARTTLS\r\n");
+            smtp_get_response($fh);
+
+            stream_set_blocking ($fh, true);
+            stream_socket_enable_crypto($fh, true, STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT);
+            stream_set_blocking ($fh, true);
+        }
 
         fputs($fh, "EHLO $smtp_server\r\n");
         smtp_get_response($fh);