Cloud Backup Means a Vendor Can Read Your Email Forever. Local Backup Means Only You Can.

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.

You didn't remove the single point of failure. You added a second company with a standing copy of every email you've ever sent or received, plus the credentials or delegated access needed to keep pulling in new mail forever.

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.

For as long as the subscription runs, the backup provider — and, by extension, anyone who successfully compromises their systems — has continuous access to your full email history. Not a snapshot from the day you signed up. An ongoing, growing archive that gets more valuable to an attacker every year it accumulates. You've traded "my provider has my mail" for "my provider and a backup vendor both have my mail," which is strictly more exposure, not less.

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?

A copy sitting on a vendor's servers can be read by that vendor's employees under the right internal access conditions, subpoenaed by a court with jurisdiction over the vendor, exposed if the vendor is breached, or handed over if the vendor is acquired by a company with different data-handling norms than the one you originally trusted. None of those outcomes require anything to go wrong on your end. They're properties of the copy existing on someone else's infrastructure at all.

A copy sitting on your own disk has exactly one of those risk categories: your own device security. That's a real responsibility — full-disk encryption, a locked-down machine, your own backup of the backup if you want extra redundancy — but it's a bounded, single risk you control directly, not an open-ended one you're trusting a third party to manage on your behalf indefinitely.

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.

The format matters here too: .eml is a plain, open standard readable by any mail client, 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.