For any other users experiencing this, it was a known bug in a few modules, which simply updating those modules stopped the emails from asterisk to asterisk.
Although one required removing a line from:
crontab -e -uasterisk
*/5 * * * * [ -e /var/www/html/admin/modules/qxact_reports/import_queue_data.php ] && php /var/www/html/admin/modules/qxact_reports/import_queue_data.php
And Calendar module had to be uninstalled and reinstalled:
All the rest fixed with updating modules.