Guide · Offboarding
Remove the licence and wait thirty days and the mailbox is gone. The three ways to keep it, the exact order that matters, and the traps that catch people every week in Microsoft’s own forums.
By Alex Makey · 6 September 2026 · 7 min read · Verified against Microsoft documentation, September 2026
This is the most-asked question in Microsoft’s own support forums, and the reason is that the default outcome is bad: remove the licence, wait thirty days, and the mailbox is gone. Here is what actually happens, the three ways to keep the data, and the order that matters.
The moment the licence is removed, the user can no longer sign in to Exchange Online. Mail sent to the address is still accepted for a short while, then bounces. OneDrive follows its own retention setting (default 30 days after the account is deleted, not after the licence is removed).
For the next thirty days the mailbox is soft-deleted. It exists, it can be restored by reassigning a licence, and nothing has been lost. This is a grace period, not a guarantee — Microsoft describes the timing as approximate.
After thirty days the mailbox is purged unless a hold was in place. Purged means gone. There is no support ticket that brings it back.
The exception is a mailbox under litigation hold or a retention policy: instead of being purged it becomes an inactive mailbox — invisible in the address book, costing nothing, searchable through eDiscovery for as long as the hold lasts.
Convert to a shared mailbox. The right answer for most leavers. The mailbox keeps everything, needs no licence up to 50 GB, and colleagues who need the history are given access. Convert while the licence is still assigned, then remove the licence. Do it the other way round and the conversion fails.
Put it on litigation hold. The right answer when the record might matter later — anyone client-facing, anyone in a regulated role, anyone leaving under a cloud. Requires an Exchange Online Plan 2 licence (included in E3 and E5) at the moment the hold is placed. Then remove the licence; the mailbox becomes inactive and costs nothing.
Keep the licence. The expensive answer, and the one people default to by not deciding. Sometimes right for a short handover period. Never right for the eleven leavers from 2023 who are still on the bill.
Connect to Exchange Online, then:
Set-Mailbox -Identity leaver@contoso.com -Type Shared
Add-MailboxPermission -Identity leaver@contoso.com -User manager@contoso.com -AccessRights FullAccess -AutoMapping $true
Set-Mailbox -Identity leaver@contoso.com -ForwardingAddress manager@contoso.com -DeliverToMailboxAndForward $trueFor a hold instead of a conversion:
Set-Mailbox -Identity leaver@contoso.com -LitigationHoldEnabled $trueThen remove the licence in the admin centre or with Microsoft Graph. Check the result a day later with Get-Mailbox leaver@contoso.com | Select RecipientTypeDetails, LitigationHoldEnabled.
The 50 GB limit. A shared mailbox over 50 GB, or with an archive, or on litigation hold, needs an Exchange Online Plan 2 licence. Check the size before converting: Get-MailboxStatistics leaver@contoso.com | Select TotalItemSize.
Converting after removal. The most common mistake. Once the licence is gone the mailbox is soft-deleted and Set-Mailbox -Type Shared fails. Reassign a licence, wait for the mailbox to reactivate, convert, remove again.
Forwarding on the user. Forwarding set on a user mailbox stops working when the mailbox is soft-deleted. Set it on the shared mailbox after conversion.
OneDrive. Files are retained for the period set in the SharePoint admin centre (default 30 days) after the user is deleted, not after the licence is removed. Assign a manager as secondary owner before deleting, or extend the retention.
The hold and the licence. The hold has to exist before the licence is removed. Remove first and the mailbox is purged after thirty days, hold or no hold.
Convert to shared by default. Hold for anyone whose record might be needed in a dispute. Review shared mailboxes once a year and delete the ones nobody has opened. That policy costs nothing, keeps every leaver’s mail, and removes the licence the day they leave — which, across a company of a few hundred, is usually the largest single licensing saving available.
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Related questions
The mailbox is soft-deleted and held for about thirty days, during which it can be restored by reassigning a licence. After that it is permanently purged unless a litigation hold or retention policy was in place, in which case it becomes an inactive mailbox.
Yes. Convert the mailbox to a shared mailbox while the licence is still assigned, then remove the licence. Shared mailboxes need no licence up to 50 GB. Alternatively, place the mailbox on litigation hold before removing the licence and it becomes an inactive mailbox at no cost.
Almost always because the licence had already been removed. A soft-deleted mailbox cannot be converted. Reassign a licence, wait for the mailbox to reactivate, convert it, then remove the licence.
Yes, when it exceeds 50 GB, uses an archive, or is placed on litigation hold. In those cases it needs an Exchange Online Plan 2 licence.
No. The hold must be in place before the licence is removed. Remove the licence first and the mailbox is purged after the grace period regardless of the hold you intended to apply.
Rather not do this yourself?
Describe the situation and you get back a sequence, an honest view of what will be slow, and a fixed price — usually within one business day. Or ask one question and get one answer.