diff --git a/PHPCI/Helper/MailerFactory.php b/PHPCI/Helper/MailerFactory.php
index b0ec4860..4eb57c13 100644
--- a/PHPCI/Helper/MailerFactory.php
+++ b/PHPCI/Helper/MailerFactory.php
@@ -28,11 +28,19 @@ class MailerFactory
      */
     public function getSwiftMailerFromConfig()
     {
+        $encryptionType = $this->getMailConfig('smtp_encryption');
+
+        // Workaround issue where smtp_encryption could == 1 in the past by
+        // checking it is a valid transport
+        if ($encryptionType && !in_array($encryptionType, stream_get_transports())) {
+            $encryptionType = null;
+        }
+
         /** @var \Swift_SmtpTransport $transport */
         $transport = \Swift_SmtpTransport::newInstance(
             $this->getMailConfig('smtp_address'),
             $this->getMailConfig('smtp_port'),
-            $this->getMailConfig('smtp_encryption')
+            $encryptionType
         );
         $transport->setUsername($this->getMailConfig('smtp_username'));
         $transport->setPassword($this->getMailConfig('smtp_password'));