Best Email Retention and Legal Hold Tools (2026)

The best email retention and legal hold tools do two opposite jobs at once. On a normal day they delete mail on a schedule, so a mailbox does not keep records past their useful life. On the day a lawsuit lands, they stop deleting anything relevant and hold it untouched. Buying for one job and forgetting the other is how organisations either hoard mail they should have purged or destroy mail they were legally required to keep.

This is policy-side tooling, and it is a different purchase from archiving (a searchable long-term store) or eDiscovery review (finding and reviewing what you preserved). The buyer here is writing policy: an automatic deletion schedule, per-user holds that override it, and a plan for when those two rules collide. We build AI Emaily, an AI email client — not a retention, legal-hold, or eDiscovery platform — so we are not a row in the table below. This article is general information about how these tools work, not legal advice; for your own duties, ask a qualified lawyer.

The short answer#

If you run Microsoft 365, the native answer is Microsoft Purview — retention policies and retention labels for the automatic deletion schedule, and eDiscovery holds (or the older Litigation hold) for preservation. If you run Google Workspace, Google Vault is the equivalent: retention rules plus holds, available on certain Workspace editions or as a per-user add-on.

If you are in a regulated industry, run a mixed estate, or need write-once immutable storage and a regulator-accepted audit trail, a dedicated platform earns its keep: Mimecast, Proofpoint Archive, Smarsh Enterprise Archive, Global Relay Archive, and Barracuda Cloud Archiving Service for cloud, or MailStore Server for on-premises. All of them share one behaviour that matters more than any feature list.

How we compared#

We compared these tools on dimensions a policy owner decides on, using vendor documentation rather than a hands-on bake-off. Five dimensions matter: platform coverage; the automatic deletion schedule — whether you can set retention or deletion by mailbox, group, or content type without touching each account by hand; legal hold per custodian and case; and, most important, what happens when a hold and a deletion rule conflict.

Fifth is storage shape and packaging. Regulated firms often need WORM immutable storage and a tamper-evident audit log, which not every tool provides. We describe packaging shape — native to a platform, per-user subscription, self-hosted — and never print a price, because these are negotiated and move. Check the vendor's own pricing and compliance pages before you buy.

The one behaviour that decides most of it: if your policy deletes mail after three years and a lawsuit makes a four-year-old message relevant, does the tool preserve it without you having found and copied it by hand first? Every tool below answers yes, through a legal hold that overrides the schedule. A tool that cannot do that is an archive or an export, not a retention-and-hold system.

Comparison at a glance#

Packaging shapes range from native platform licensing (Purview, Vault) through per-user cloud subscriptions (Mimecast, Proofpoint, Smarsh, Global Relay, Barracuda) to a self-hosted per-user licence (MailStore Server). Most offer a trial or a proof-of-concept; verify the current edition, licensing and compliance certifications on the vendor's own page before committing. Prices are deliberately not printed here — they change and are usually negotiated.

Does a legal hold override a retention policy?#

Yes. This is the single most important thing to understand before you configure any of these tools, and every serious platform resolves it the same way: preservation beats deletion. A retention or deletion schedule runs in the background; a legal hold sits on top of it and suspends deletion for the data it covers. Miss this and you can build a deletion policy that quietly destroys evidence during litigation — which courts treat far more harshly than the awkward email itself.

Microsoft states the rule in its Purview retention documentation: "By default, retention always takes precedence over permanent deletion, and the longest retention period wins." When several settings collide, its published principles determine the outcome. Crucially, Microsoft adds that items under an eDiscovery hold "cannot be permanently deleted by any retention policy or retention label," and that when the hold is released, the normal principles resume (verified on Microsoft Learn, July 2026 revision).

Google Vault is just as explicit: "Holds take precedence over retention rules," and "when a hold is deleted, data is immediately subject to applicable retention rules." Barracuda's documentation says the same — litigation holds override its Saved Search and Global Retention policies for as long as the hold is in place. The mechanism is universal; only the button names differ.

Picture the two rules as forces pulling on one message. The retention schedule pulls toward deletion at a fixed date. The legal hold pulls toward preservation, indefinitely, for as long as it is active. When both apply to the same message, the hold wins and deletion is suspended — not deleted-then-recovered, but never deleted in the first place. Release the hold and the deletion force takes over again from where it left off.

GDPR: data minimisation versus retention duties#

The reason retention is a policy decision and not a checkbox is that two legal pressures push in opposite directions. The GDPR's storage-limitation principle (Article 5(1)(e)) says personal data should be kept in an identifiable form no longer than is necessary for the purpose it was collected for. Its data-minimisation principle (Article 5(1)(c)) says you should only hold data that is adequate, relevant and limited to what is necessary. Read alone, both push you to delete mail sooner (verified against Regulation (EU) 2016/679 on EUR-Lex).

Pushing the other way are laws that require you to keep records for years — tax rules, employment records, and sector rules such as SEC and FINRA requirements that demand immutable, accessible archives. The GDPR allows this: it permits keeping personal data where you have a legal obligation or need to establish or defend legal claims. Minimisation and retention are a balance to document per record type, not a contradiction.

In practice this means your automatic deletion policy software should not delete everything as early as possible, nor keep everything forever. It should delete on a schedule tuned to each record's real legal and business need, and a legal hold should be able to freeze that schedule the moment litigation is reasonably foreseeable. The tools above give you the levers; deciding where to set them is a legal judgement, not a default.

1. Microsoft Purview (with eDiscovery holds)#

For a Microsoft 365 tenant, Purview is the native answer and usually the right one. Its Data Lifecycle Management applies retention policies at a location — all mailboxes, or an adaptive scope — and retention labels at the item level, so a specific message or folder can carry its own rule. Labels are treated as explicit, which is why a label's delete action takes precedence over a broader policy's.

Preservation is a separate mechanism: create an eDiscovery hold (the older Litigation hold on an Exchange mailbox still works, though Microsoft now recommends Microsoft 365 retention or eDiscovery holds instead). A hold makes the mail undeletable by any retention rule until you release it. Microsoft frames retention as a compliance tool with low administrative overhead, and eDiscovery holds as a legal tool with high overhead — a useful reminder that a hold is a deliberate, tracked act, not a background setting.

Where it loses: fuller data-lifecycle and eDiscovery capabilities sit in higher Microsoft 365 tiers or add-ons; check what your licence includes before assuming a feature is on. Confirm current behaviour on Microsoft Learn.

2. Google Vault#

Google Vault is the Purview equivalent for Google Workspace: it sets Gmail retention rules (default and custom, by organisational unit or query) and places holds on specific users' Gmail so it survives past any retention rule. Vault also covers Drive, Chat, Meet recordings and Groups, so preservation spans more than email.

The precedence rule is stated cleanly in Google's own help: holds take precedence over retention rules, and data under a legal hold is not purged; only when the hold is removed does the retention rule apply again. That makes Vault predictable for exactly the conflict that matters. Retention rules also let you purge mail that users deleted, which is how an organisation enforces deletion rather than leaving it to each person.

Where it loses: Vault is included only on certain Workspace editions or requires a per-user licence. It is a retention and discovery tool, not a full continuity or supervision suite — regulated firms often layer a dedicated archive on top.

3. Mimecast Cloud Archive#

Mimecast is a long-standing choice when email lives across more than one platform, or when continuity matters as much as retention. Its Cloud Archive is a central repository that captures inbound, outbound and internal mail, and Mimecast states it keeps three tamper-proof, encrypted copies in geographically separate data centres — the kind of durability a compliance officer wants to be able to describe.

On the two jobs this article cares about, Mimecast applies retention policies to control how long mail is kept, and a legal hold that keeps messages for at least as long as the hold is active — even when that is longer than the message's original expiry date. That is the override behaviour, worded in Mimecast's terms. Search and case tools support litigation readiness on top.

Where it loses: it is a full archiving and security platform — more than a team that only needs a deletion schedule and occasional hold. For a pure Microsoft 365 or Google shop with no multi-platform need, the native tool is simpler. Verify current capabilities on Mimecast's site.

4. Proofpoint Archive#

Proofpoint Archive is a cloud-native archiving and compliance service aimed at organisations that expect regular eDiscovery and regulatory review. It ingests email and other sources, enforces retention automatically, and gives legal teams strong search to locate and retrieve relevant communications during litigation.

For preservation, a company-wide legal hold retains all archived messages indefinitely while active, on top of per-policy retention. Proofpoint Archive carries FedRAMP authorisation, which matters to government and public-sector buyers who need an accredited service. If your dominant use case is producing records quickly and defensibly, this is squarely in its lane.

Where it loses: heavier and pricier than a small team needs for basic retention, and it is a compliance archive rather than a continuity-first product. Check the current data sheet on Proofpoint's own pages, as configurable ceilings and editions change.

5. Smarsh Enterprise Archive#

Smarsh is built for regulated industries — financial services above all — where the rules are specific and audited. Its Enterprise Archive captures email plus more than a hundred communication channels in native format with metadata, so context and searchability survive — breadth that matters when a regulator expects messaging apps and collaboration tools preserved alongside email.

On retention and hold, Smarsh supports immutable WORM storage aligned to SEC 17a-4, configurable legal holds that prevent deletion or alteration during litigation or an investigation, and defensible deletion so mail is removed on schedule in a way you can justify later. That triad — immutable capture, hold, and defensible deletion — is what a financial-services examiner tends to ask about.

Where it loses: overkill for a general business with no supervision or WORM requirement. If you are not bound by SEC, FINRA, or MiFID II rules, a lighter tool fits. Confirm current certifications on Smarsh's site.

6. Global Relay Archive#

Global Relay sits in the same regulated-communications space as Smarsh and is a common answer for financial firms that need archiving, supervision and eDiscovery in one governed system. It archives email alongside many other channels and is designed around the recordkeeping demands of regulators and audits.

For preservation, Global Relay lets you place records on legal hold by custodian, domain, case, or dynamic criteria, and it does so independently of the retention schedule — the standard override, expressed as a flexible way to scope exactly whose mail is frozen. An object change log records the actions taken on records during eDiscovery, which supports a defensible chain of custody, and exports come in accepted evidentiary formats.

Where it loses: an enterprise, regulated-firm product — a small unregulated team does not need it. Verify current coverage and compliance claims on the vendor's own pages.

7. Barracuda Cloud Archiving Service#

Barracuda's Cloud Archiving Service is a more approachable option for small and mid-sized organisations that want proper retention and holds without an enterprise-scale rollout. It archives a compliant copy of every message and lets you set granular retention policies — you can specify a number of days to keep mail, or retain it indefinitely.

Preservation is handled by litigation holds that designated auditors apply to the results of a saved search. Barracuda states that these holds override its Saved Search and Global Retention policies and can run for a defined period or indefinitely, securing the data against amendment or deletion until the hold is removed. That is the override behaviour in a package sized for a leaner IT team.

Where it loses: it does not reach the channel breadth of Smarsh or Global Relay, and heavily regulated firms may need certifications it cannot satisfy. For a Microsoft 365, Exchange or IMAP shop that wants retention plus reliable holds, it is a sensible middle option. Verify current features on Barracuda's documentation.

8. MailStore Server#

MailStore Server is the answer when you want the archive on infrastructure you own rather than a vendor's cloud. It pulls mail from Exchange, Microsoft 365, Google Workspace, IMAP and PST into a single indexed, self-hosted archive, and it is a practical fit for organisations with data-residency or control requirements that rule out a hosted service.

On policy, MailStore lets you define retention policies with a minimum of one day and a maximum of a thousand years, applied to all mail or only messages matching a search. Its Legal Hold feature temporarily prohibits deleting mail from the archive, and an integrated auditing function logs any changes — the override plus a tamper-evident trail. MailStore is regularly certified against the GDPR by independent assessors and points to HIPAA and other regimes; version 26.1 shipped in January 2026.

Where it loses: someone has to run and back up the server. For a business comfortable operating a service, it is the strongest self-hosted pick.

Where AI Emaily fits — and where it does not#

AI Emaily is an AI-native email client — triage, drafting in your voice, follow-ups, an approval-first agent — on Gmail, Outlook, iCloud and IMAP. It is not a retention, legal-hold, or eDiscovery platform, and it does not belong at the top of this table. We build AI Emaily, and telling you it is the wrong tool for a deletion schedule or legal hold is more useful than pretending otherwise.

Concretely: AI Emaily does not set organisation-wide retention rules, it does not place a legal hold on a mailbox, and nothing it does makes a message un-discoverable or overrides your employer's retention. Those jobs belong to Purview, Vault, or one of the dedicated archives above. If a lawyer tells you to preserve, use the hold in your retention tool — not your mail client.

What we genuinely help with is the live inbox that sits in front of all of this: approve-before-send so a mistaken bulk reply is caught before it becomes a record you have to preserve, an audit log of what the agent did, and no training on your mail. Pair a real retention-and-hold tool with a client like ours; they solve different problems. AI Emaily runs on a 7-day free trial (Pro or Autopilot, card required, $0 if cancelled before day 7) — see our pricing page for current details, and our security page for how we handle data.

How to choose for your situation#

Start with the platform you already run, then decide whether you are regulated and where the archive must physically live. Those three answers usually name the tool.

• Microsoft 365 tenant, not heavily regulated: use Purview retention policies and labels for the schedule and eDiscovery holds for preservation. Check what your licence tier actually includes first.
• Google Workspace tenant: use Google Vault for both retention rules and holds. Confirm your edition includes Vault or budget for the add-on.
• Regulated financial-services firm needing WORM storage and supervision: Smarsh Enterprise Archive or Global Relay Archive, which are built for SEC, FINRA and MiFID II-style recordkeeping.
• Mixed estate or continuity matters as much as compliance: Mimecast Cloud Archive; for eDiscovery-heavy or public-sector needs, Proofpoint Archive.
• Small or mid-sized team that wants proper retention and holds without enterprise scale: Barracuda Cloud Archiving Service.
• Data must stay on infrastructure you control: MailStore Server, self-hosted, with retention policies and a Legal Hold feature.

How long should a company retain email?#

There is no single number. Retention length is set per record type by the laws you are subject to (tax, employment, sector rules), your own business need, and whether a legal hold is in force. Some records must be kept for years; others should be deleted once no longer needed, to satisfy data-minimisation duties.

A workable pattern is to classify mail into a few retention buckets — routine correspondence on a short schedule, contracts and financial records on a longer one, regulated categories on whatever the rule specifies — and let the tool enforce each bucket automatically. Layer legal hold on top so any bucket can be frozen the instant litigation is foreseeable. Then document why each period is set where it is, because a regulator or opposing counsel may ask you to defend both the keeping and the deleting.

Keeping everything forever raises GDPR exposure and discovery cost; deleting too aggressively risks destroying records you were required to keep. The right period is a legal judgement per record type — decide it with counsel, then configure one of the tools above to hold the line.