XCloner Joomla and WordPress backup notification emails are not beng delivered. Postfix Mail logs (/var/log/maillog) shows that email was bounced by Google because of sender's domain noreply.com
After a bit of digging I found that noreply.com was coming from cloner.cron.php file located in administrator/components/com_xcloner-backupandrestore (in case of Joomla). At line 437 there was following code:
cron_fromlogemail variable seems to be exposed in GUI only in the latest Joomla 3.X version of XCloner.