public function toMail($notifiable) : MailMessage
{
$mailMessage = (new MailMessage())->subject("Clean up of `{$this->applicationName()}` backups successful")->line("The clean up of the {$this->applicationName()} backups on the disk named {$this->diskName()} was successful.");
$this->backupDestinationProperties()->each(function ($value, $name) use($mailMessage) {
$mailMessage->line("{$name}: {$value}");
});
return $mailMessage;
}