In short
Exchange Online backup keeps a separate copy of your mailboxes, calendars and contacts beyond Microsoft's native safety nets. By default Exchange Online keeps deleted items for 14 days (30 at most) and a deleted mailbox for 30 days. A backup lets you restore single emails, whole mailboxes or leavers' mail long after those windows close.
Get a quote for Exchange Online backup
Tell us roughly how many users or sites you have and we will reply by email with options and a quote.
What Exchange Online keeps on its own
Exchange Online has several layers of protection before anything is gone for good, and it is worth knowing exactly where each one ends.
| Safety net | What it does | Where it stops |
|---|---|---|
| Deleted Items folder | Holds items a user deletes until they empty it or a policy clears it | Users can empty it at any time |
| Recoverable Items folder | Holds items deleted from Deleted Items, or deleted with Shift+Delete, for the deleted item retention period | 14 days by default, 30 days at most; calendar items 120 days |
| Recoverable Items quota | Limits how much the folder can hold | 20 GB warning and 30 GB limit, rising to 90 GB and 100 GB for mailboxes on hold or under retention |
| Soft-deleted mailbox | Keeps a mailbox after its user account is deleted | 30 days, then the mailbox is permanently removed |
| Licence removal | Keeps the mailbox when an Exchange Online licence is removed | A 30-day grace period, after which the mailbox is deleted |
| Holds and retention policies | Preserve content for compliance, and can keep a leaver's mailbox as an inactive mailbox | Built for search and export through eDiscovery, not for putting mail back |
The pattern is the same throughout: generous enough for a user who deletes the wrong email this morning, short for anything discovered next quarter. Microsoft 365 recycle bin sets out every workload's windows side by side, and Microsoft 365 backup vs retention explains why holds are not a substitute for a backup.
Not sure which option fits? Ask us
Tell us what you need and we will recommend the right option for your organisation, with a quote.
Why mailboxes need a backup
These are the situations where the native windows run out:
| Situation | Native route | With a backup |
|---|---|---|
| A user purges a folder, and nobody notices for six weeks | Recoverable Items only reaches back 14 to 30 days | Restore the folder from a point before the deletion |
| A leaver's account was deleted two months ago and their mail is now needed | The soft-deleted mailbox has gone after 30 days unless a hold kept it | Restore the mailbox, or export it, from the backup |
| A compromised account deletes mail and creates rules | Partial recovery from Recoverable Items, if within the window | Restore the mailbox to its state before the compromise, without overwriting newer mail |
| A migration or script corrupts many mailboxes | Item-by-item recovery at best | Point-in-time restore of each mailbox |
| Someone needs a copy of a mailbox to keep or hand over | eDiscovery export, if the content is held | Export from the backup, as PST where the platform supports it |
Leavers are the most common trigger. Removing a licence or deleting an account starts a 30-day clock, and many organisations only realise a mailbox matters after the clock has run out.
What to include in an Exchange Online backup
- User mailboxes: mail, attachments and folders, plus calendars and contacts, which people miss most when they are gone
- Shared mailboxes: sales@, accounts@ and similar inboxes often hold the organisation's most important threads
- Group mailboxes: the mailboxes behind Microsoft 365 groups and teams, which Microsoft 365 Backup does not cover
- Archive mailboxes: in-place archives hold older mail that users still expect to find
- Public folders: still in use in some organisations, and only some platforms back them up
- Leavers: decide how long a departed user's mail is kept in backup, and how that affects licensing
Is Exchange Online backup the right fit for you?
We will check it against your systems and requirements and recommend the right option.
Exchange Online backup coverage by platform
Every platform we supply backs up Exchange Online. The differences are in which mailbox types are included and how you search, restore and export.
| Platform | Mailboxes and data covered | Restore and export |
|---|---|---|
| Acronis Backup for Microsoft 365 | User, shared and group mailboxes: email, calendars and contacts, with optional in-place archive mailboxes | Search by sender, recipient, subject or date; restore single items to the original or another mailbox |
| Axcient x360Cloud | Exchange Online mail, calendars and contacts | SmartSearch full-text search, including attachments; non-destructive, point-in-time and granular restore; browser export and PST export |
| NinjaOne SaaS Backup for Microsoft 365 | Inbox, sent items, folders, attachments, calendar and contacts | Restore a single email, a folder or a whole mailbox from any point in the backup timeline, avoiding overwriting intact content; audit log |
| Redstor backup for Microsoft 365 | Mailboxes, calendars and contacts, from a whole account to a single email and its attachments | InstantData streams mailboxes back while the full restore runs; granular and point-in-time restore |
| Commvault backup for Microsoft 365 | Exchange Online including public folders, shared and group mailboxes; archive mailboxes and recoverable items in the Enterprise editions | Export to PST or CAB; granular, point-in-time restore in place or elsewhere; self-service restore in the Enterprise editions |
| Microsoft 365 Backup (Microsoft) | User and shared mailboxes only; not group or room mailboxes | Full mailbox or item-level restore to the same or a new folder; recovery points every 10 minutes |
Commvault's edition names and allowances are per its current edition guide and confirmed at quote. If public folders or archive mailboxes matter to you, say so early, because they narrow the choice.
Restoring Exchange Online mailboxes
A good mailbox restore is precise and does not trample on anything that has arrived since. Look for:
- Granular restore: a single email, calendar entry, contact or folder, not just whole mailboxes
- Point in time: choose the moment before the deletion or compromise
- Non-destructive restore: put items back without overwriting newer mail, or restore to a separate folder or mailbox
- Alternate location: restore a leaver's mail into a manager's mailbox or a shared mailbox
- Export: download a mailbox or folder to hand over or keep, as PST where the platform supports it
If a mailbox has already been deleted, start with Microsoft's own route while it is still within 30 days: our guide to how to restore a deleted mailbox walks through it, and covers restoring from a backup once the window has closed. The wider Microsoft 365 backup and restore guide covers other scenarios.
Backup, journaling and archiving
A backup is for getting mail back after it has been lost or damaged. Archiving and journaling are for keeping a tamper-evident record for compliance, search and legal requests, and they answer different questions: "how long must we keep this email?" rather than "how do we get it back?".
If your requirement is a compliance record, see Exchange Online journaling and leavers' mailboxes on our email archiving site. Some bundles do both: NinjaOne SaaS Backup + Archiver and Redstor's Comply Bundle add email archiving to backup.
How we help
We count your user, shared and group mailboxes, check for archive mailboxes and public folders, agree how long leavers' mail should be kept, then recommend a platform and edition that covers them. We can set up the backup, check the first runs complete and run a test restore of a mailbox folder with you, so you know the process before you need it. Licences, renewals and user changes stay on one Forever Systems account, with terms confirmed at quote.
Contact us to talk about protecting your Exchange Online mailboxes.
How Forever Systems helps with Microsoft 365 backup
We are an independent UK IT and cyber security provider. We supply more than one Microsoft 365 backup product, so we can recommend what fits your tenant, your retention needs and your budget rather than one vendor's answer to everything.
- Review what you have: we look at your Microsoft 365 licences, retention policies and any existing backup before suggesting anything new
- Help you choose: we compare the backup products we supply against the workloads you need covered, such as Exchange Online, OneDrive, SharePoint, Teams and Entra ID
- Set-up and onboarding: we can help connect the backup service to your tenant and agree what is protected and how long copies are kept
- Restore testing: we can help you plan and run test restores so you know how recovery works before you need it
- Licensing in one place: backup licences alongside your Microsoft 365 subscriptions, with terms confirmed at quote
We work with businesses, schools, charities and public sector organisations. Contact us to talk it through.
Frequently asked questions
Does Exchange Online have a backup?
Exchange Online keeps deleted items for 14 days by default (up to 30) and deleted mailboxes for 30 days, and Microsoft sells Microsoft 365 Backup separately. None of these is an independent copy kept to your own retention policy, which is what a third-party Exchange Online backup provides.
How long are deleted emails kept in Exchange Online?
Items in the Recoverable Items folder are kept for 14 days by default, and an administrator can raise this to 30 days. Calendar items are kept for 120 days. After that they are purged unless a hold or retention policy keeps them.
Can I back up a shared mailbox?
Yes. All the platforms we supply list shared mailboxes or Exchange Online mailboxes generally, and Microsoft 365 Backup covers user and shared mailboxes. How shared mailboxes are licensed differs by vendor; we confirm it at quote.
Can I export a backed-up mailbox to PST?
With some platforms. Axcient x360Cloud and Commvault both list PST export. Other platforms restore into a mailbox, from where Microsoft's own tools can export. Tell us if PST export matters and we will factor it in.
Is litigation hold a backup for Exchange Online?
No. Holds preserve content so it can be found and exported through eDiscovery. Microsoft says legal holds are optimised for export rather than mass restore, so they do not replace a backup for recovery.
Still have a question about Exchange Online backup?
Ask us and a member of our team will reply by email.