OnApp: Failed Backup Schedule Notification

You can enable those notifications in Product settings > Emails > Client Notifications.

Change Automated Backup Failed option from None to one of your email templates.

Example Email Template

This shows an example message  with variables that can be used in this template.

Dear {$client.firstname} {$client.lastname}

Some automated backups failed for account #{$service.id} {$service.domain}:
{foreach from=$vms item=vm}
{$vm.hostname} - {$system_url}{$ca_url}clientarea/services/{$service.slug}/{$service.id}/&vpsid={$vm.id}&vpsdo=vmdetails
{foreach from=$vm.schedules item=schedule}
{if $schedule.target_type == 'Disk'}* Disk #{$schedule.target_id}{/if} backup every {$schedule.duration} {if $schedule.period=='weeks'}week(s){elseif $schedule.period=='days'}day(s){elseif $schedule.period=='months'}month(s){elseif $schedule.period=='years'}year(s){/if} failed.