Yes, you can order a Backup-MX service from us for your (external) domain.
With a Backup-MX, our customer relay accepts emails for your domain, when your primary mail server is unavailable.
As soon as availability is restored, the cached emails are automatically delivered to your server again.
If you would like to order our Backup-MX service, please contact our support team by emailing email@example.com.
Please let us know your customer number and your service pin.