Cloud Email Backup and Local Archives: Who Can Access the Copy?

Once someone accepts that their inbox isn't a backup — and it isn't, we've made the case for that in detail — the next instinct is usually to reach for another cloud product to fix it: a third-party backup service that connects to Gmail or Microsoft 365 and continuously copies everything to its own servers. It feels like solving the problem. Structurally, it's closer to relocating it.

A cloud-to-cloud backup can create an independent recovery copy, while adding another service and access grant to evaluate. How long it retains mail and who can read that copy depend on its configuration, encryption and contract.

What a Cloud Backup Vendor Actually Holds

The architecture behind most cloud email backup products is straightforward: the service connects directly to your mail server via API or protocol-level access, duplicates every message and attachment, and stores that archive on servers the backup provider operates and manages — not you. That's the entire value proposition; it's also the entire risk surface.

A continuously updated backup may retain a growing message history. Assess the service’s delegated permissions, retention, encryption keys and restore controls, including what happens when access is revoked or the subscription ends. A second copy can improve recovery while introducing different access risks.

None of this makes cloud backup vendors negligent or badly run. Reputable ones invest seriously in security. The point is structural, not a judgment about any specific company: centralizing more copies of sensitive data in more places controlled by other organizations increases the number of ways it can go wrong, no matter how well each individual party executes.

The Question That Actually Matters

When you're evaluating any backup approach for email, the question isn't just "does a copy exist somewhere else." It's: who can read that copy, and for how long?

Access depends on the service’s encryption, key ownership and permissions. A provider holding decryption keys may be able to access stored mail; a properly implemented client-side encrypted backup can limit that access. Check the specific service’s policy, deletion terms and restore process rather than assuming every cloud copy is readable by its vendor.

A local copy depends on device security, disk health, physical access and your backup arrangement. MailVault’s message files are not an encrypted vault by themselves. Use disk encryption and a separate tested backup; if you place those files in a cloud-synchronized folder, that service also becomes part of the storage arrangement.

Local Backup Also Just Survives More Things

Beyond the access question, a local copy is resilient to a specific list of failures that a cloud-to-cloud backup doesn't actually solve: the backup vendor raising prices or shutting down, the backup vendor's own service going through an outage exactly when you need to restore, a subscription lapsing because a card expired, or the vendor changing its terms of service in a direction you wouldn't have agreed to today. A file on your disk doesn't have a subscription status. It's just there.

How MailVault Is Built Differently

MailVault connects to your existing IMAP or OAuth email account and archives every folder as individual .eml files — written straight to your own disk. There's no MailVault-operated server holding a copy of your mail in the middle. We can't read your archive, because we never receive it; the connection is between your device and your provider, and the resulting files live only where you put them. These file-layout instructions use the default Maildir format. Settings → Storage also offers JMAP storage, which keeps original message bytes with JSON records and deduplicates identical messages.

The format matters here too: .eml is a plain, open standard readable by mail apps supporting EML, not a proprietary database that locks your archive to one piece of software or one company's continued existence. Manual, unlimited local backups are free, full stop. Scheduled backups that keep the archive current automatically, without you remembering to run one, are a $4/month or $25/year premium feature — the yearly plan includes a 14-day trial.

Related reading: what to actually look for in an IMAP backup tool, how to archive IMAP emails locally, and a MailStore alternative for Mac.