What Restow does

By Lucas Flores, IT Systeme Flores UG. Last updated 2026-09-30

In short: Restow backs up and restores Microsoft 365 and IMAP mailboxes to storage you control, and checks that every backup actually restores rather than just reporting success.

Restow backs up and restores Microsoft 365 (Exchange Online mail, calendar and contacts, and OneDrive) and any IMAP mailbox, deduplicates and encrypts everything before it is stored, and checks that what it backed up can actually be read back, because a backup nobody has restored is a theory, not a guarantee. It also backs up Linux and macOS servers and clients with an agent, and imports and exports mail files. The eight pages below cover one part each; read the one you need, or all eight for the full picture. Every page states current limits honestly, next to the feature, not in fine print elsewhere.

Eight pages, one topic each

Microsoft 365 and IMAP backup: What's protected today, incremental via Microsoft Graph delta queries, and the limits stated plainly.
Server and client backup: A Linux and macOS agent, append-only, restores into a new folder, and the limits stated plainly.
Mail file import and export: EML, MSG, MBOX and MailStore exports in, EML in a ZIP or MBOX out. PST is planned, not shipped.
Non-destructive restore by default: Granular or complete, into the same account or a different one, non-destructive by default.
Automated restore verification: Why an unread backup is unproven, and what's checked today versus still in development.
Storage: local disk, S3, NFS or SMB: Deduplicated, encrypted chunks on infrastructure you choose, with no Restow-operated cloud.
Encryption and key handling: AES-256-GCM per organization, and exactly who can (and can't) read your data.
Multi-tenancy for service providers: One installation, many isolated tenants, delegated administration and per-tenant reporting.

For what's shipped, what's actively being built and what's honestly just planned (including the archive layer and the Windows agent; the Linux and macOS agent already ships), see the full roadmap. For what any of this costs, see pricing: backup and restore are never limited by edition or mailbox count; multi-tenancy (delegated administration across tenants) is a Service Provider feature, see the pricing page for the exact split.