Fix "forcing" client certificate for SMTP

conf/app.ini

@@ -105,6 +105,10 @@ SUBJECT = %(APP_NAME)s
 HOST =
 ; Do not verify the certificate of the server. Only use this for self-signed certificates
 SKIP_VERIFY = 
+; Use client certificate
+; USE_CERTIFICATE = true
+; CERT_FILE = custom/mailer/cert.pem
+; KEY_FILE = custom/mailer/key.pem
 ; Mail from address, RFC 5322. This can be just an email address, or the "Name" <email@example.com> format 
 FROM =
 ; Mailer user name and password