In short
Email archiving is the practice of capturing a copy of every email sent and received, usually by journaling, and storing it unaltered in a separate, searchable repository for a set retention period. Organisations use an archive to prove what was said, meet record-keeping duties, answer disputes and information requests, and keep leavers' mail without keeping their mailboxes.
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Email archiving in plain English
Email is where much of an organisation's business happens: quotes, agreements, instructions, complaints, approvals. Mailboxes are poor places to keep that record. Users delete and move mail, mailboxes fill up, accounts are removed when people leave, and nothing in a normal mailbox proves a message has not been changed.
An email archive solves this by taking its own copy. Each message is captured as it passes through the mail system, stored in a repository that does not allow edits or early deletion, indexed for search, and kept for as long as your retention policy requires. When the period ends, it can be deleted in a controlled way. Throughout, a log records who has searched or exported what.
A good way to think of it: the mailbox belongs to the user; the archive belongs to the organisation.
What an archive is for
Organisations usually set up an archive for one or more of these reasons:
- Proof: showing exactly what was sent, to whom and when, in a contract dispute, an employment matter or a complaint.
- Record keeping: keeping categories of mail for the periods your policy, your sector or the law requires. Our guide how long should a company keep emails? sets out the UK reference points.
- Discovery: finding every relevant message quickly when a solicitor, regulator, auditor or individual asks. See email eDiscovery.
- Subject access requests: searching mail, including former employees' mail, for an individual's personal data. See searching email for subject access requests.
- Leavers: keeping a former employee's mail searchable after their account and licence are gone. See what to do with a former employee's mailbox.
- Defensible deletion: deleting mail on schedule once it is no longer needed, which UK GDPR's storage limitation principle expects.
Outlook's Archive folder and Gmail's Archive button are not archives
The word "archive" is used for several different things, which causes confusion.
| Feature | What it actually does | A compliance archive? |
|---|---|---|
| Outlook Archive button and folder | Moves messages to an Archive folder in the same mailbox. Microsoft notes it does not reduce mailbox size. | No |
| Gmail Archive button | Removes a message from the inbox; Google says you can still find it under All Mail. A reply brings the conversation back to the inbox. | No |
| Microsoft 365 archive mailbox (Online Archive) | A second storage area for older mail, inside the same tenant, used to keep primary mailboxes small | Storage, not a separate record |
| Journaling email archive | Captures a copy of each message at the mail server and stores it unaltered for a set period | Yes |
The first two simply move mail around inside the user's own mailbox. The user can still delete it, and if the account is removed, the mail goes with it. Microsoft's archive mailbox is useful for storage and can be combined with Microsoft Purview retention and holds, as our page on Exchange Online Archiving explains, but it remains part of the tenant it protects. A compliance archive is a separate, controlled copy.
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How mail gets into an archive: journaling and import
There are two ways mail reaches an archive.
Journaling is the standard method for new mail. The mail system is configured to send a copy of every inbound and outbound message, with its envelope details, to the archive's journal address. Because the copy is taken at the server as the message flows, it does not matter whether the user later deletes or edits their own copy. Our page on email journaling explains how it works.
Import brings in mail that existed before journaling started: an old archive, PST files or EML exports. With NinjaOne Archiver, existing mail in a mailbox is backed up when the mailbox is added, and NinjaOne offers an ingestion service for legacy PST and EML files. See migrating a legacy email archive.
Journaling only captures mail from the day it is switched on, so planning the import of older mail is part of setting up any archive.
Immutability, retention and deletion
Three ideas make an archive trustworthy.
Immutability. Archived messages are held in write-once, read-many (WORM) storage. Nobody, including an administrator, can edit a message, and it cannot be deleted before its retention period ends. That is what gives the archive its value as evidence.
Retention. Each message is kept for a period set by policy. Good policies are set by category of mail rather than "keep everything forever", which costs more and conflicts with UK GDPR's requirement not to keep personal data longer than necessary. NinjaOne Archiver supports retention from 30 days to over a decade, or indefinitely, with policies by user, department or domain. Our email retention policy guide shows how to decide the periods.
Deletion and hold. When a retention period ends, mail can be deleted in a controlled, logged way. If a dispute or investigation is reasonably anticipated, a legal hold overrides deletion for the mail concerned until it is lifted.
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Who searches an archive
An archive is not usually searched by IT. It is searched by the people responsible for compliance, data protection, HR and legal matters, and access is controlled by role.
In NinjaOne Archiver, the End-User Portal has compliance roles that exist only on the Archiver plans: Compliance and Review Officer, Data Protection Officer, Reviewer and Limited Reviewer. The IT Admin role cannot access the compliance features at all, which keeps sensitive searches with the people who should run them (the Full Admin role can see everything, so keep it to very few people).
Compliance and Review Officers and Data Protection Officers run eDiscovery searches by email account, date range, sender, recipients and keywords, with AND/OR logic; they can save searches, tag results, set alerts and flag results for review. Reviewers and Limited Reviewers work only in the review processes they are given, marking assigned items as reviewed. Only Data Protection Officers can delete eDiscovery searches or carry out deletions in a review.
That separation matters when the archive is used for an HR investigation or a subject access request, where the people who run IT should not necessarily see the results.
Common misconceptions about email archiving
- "Our mail is in the cloud, so it is archived." Microsoft 365 and Google Workspace keep mail running, but what users delete can be lost once recycle bins and retention settings run out, unless you have set retention or an archive to keep it.
- "We keep everything, so we are covered." Keeping all mail indefinitely is not a policy. It makes searches slower and riskier and sits uneasily with UK GDPR's storage limitation principle.
- "The Archive folder is our archive." It is a folder in the user's mailbox, and the user can still delete what is in it.
- "A PST on a file share is an archive." PST files can be edited, copied, lost or corrupted, and they are hard to search across users. They are better imported into a proper archive.
- "Archiving is only for big or regulated firms." Disputes, subject access requests and leavers affect organisations of every size, and per-user licensing makes an archive practical for small teams too.
Archiving and backup are different jobs
A backup takes scheduled copies so you can restore lost or damaged data. An archive captures every message as it is sent or received and keeps it unaltered and searchable for a set period. Most organisations need both, and NinjaOne's Archiver bundles include both. The full comparison is on email archiving vs backup.
If you are weighing up whether you need an archive, our buyer's guide to email archiving software has a checklist, and you can contact us to talk it through.
How Forever Systems helps with email archiving
We are an independent UK IT and cyber security provider. We supply NinjaOne SaaS Backup with Archiver for organisations on Microsoft 365 or Google Workspace, and help you get the archive set up, the policies right and the people who need it confident using it.
- Scoping: we look at your mailboxes, leavers, legacy archives and record-keeping obligations, and what your Microsoft 365 or Google Workspace plan already includes, before suggesting anything new
- Set-up: we can configure journaling for Exchange Online or Google Workspace, connect the archive and check that mail is arriving
- Retention and legal hold: we help you turn your email retention policy into archive rules, and show your compliance or HR lead how to search, hold and export
- Leavers and legacy archives: we can help you plan how former employees' mail and older archives are brought across, with the approach confirmed at quote
- Backup alongside the archive: the same NinjaOne per-user licence also covers backup of your Microsoft 365 or Google Workspace data, so recovery and record-keeping are planned together
We work with businesses, schools, charities and public sector organisations. If you also need wider protection, see our independent cloud security guides.
Frequently asked questions
What is the purpose of archiving emails?
To keep a complete, unaltered and searchable record of the organisation's email for as long as it is needed, so you can prove what was said, meet record-keeping duties, respond to disputes and information requests, and keep leavers' mail after their accounts are removed.
What does archiving an email do in Outlook?
In Outlook, the Archive button moves a message to the Archive folder in the same mailbox without deleting it. Microsoft notes it does not reduce mailbox size. It is a filing tool, not a compliance archive.
Is an archived email in Gmail deleted?
No. Gmail's Archive button removes the message from the inbox, and Google says you can still find it under All Mail. The user can still delete it, so it is not a compliance archive.
Can archived emails be deleted?
In a compliance archive, messages cannot be edited and cannot be deleted before their retention period ends. After that they can be deleted in a controlled way, unless a legal hold applies.
What is the difference between journaling and archiving?
Journaling is the capture method: the mail server sends a copy of each message to a journal address. Archiving is what happens next: storing that copy immutably, applying retention and making it searchable. See email journaling.
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