Hi TrueDuality - Giri Sreenivas, co-founder and CEO of Helm here.

We will be publishing more details to answer your questions in depth in a series of coming posts. I'll give you some quick answers right now.

We use Yocto to spin our own Linux build. Key projects we utilize: OpenLDAP Postfix Dovecot Darwin Calendar and Contacts Certbot OpenDMARC OpenDKIM OpenSSL Python SPF Policy Sieve SpamAssassin Duplicity StrongSwan Docker

We're using duplicity for backups. So you can use it to decrypt backups as you will have the keys as well. Backups are stored on a service we run using S3 and will always be accessible for the user even if something happens to the company.