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A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11To create a public folder in Office 365 (now Microsoft 365) Exchange Online, first create a public-folder mailbox, then create the folder in the Exchange admin center (EAC) or Exchange Online PowerShell. Assign appropriate folder permissions afterward. Mail-enable the folder only if people need to send messages to it.
Before you begin: create a public-folder mailbox
Exchange Online requires a public-folder mailbox before you can create a public folder. The mailbox stores the public-folder hierarchy and content. The first public-folder mailbox in an organization is the primary hierarchy mailbox, which holds the writable copy of the hierarchy; additional mailboxes hold read-only copies. See Microsoft’s public-folder mailbox setup guidance.
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Check for an existing or legacy public-folder deployment before starting a new one. Microsoft notes that a legacy deployment can prevent ordinary mailbox creation and may require migration-specific steps. The account doing the work also needs the appropriate Exchange Online role permissions; consult Microsoft’s feature-permission guidance for the role assignment that applies to your tenant.
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Create the mailbox in EAC
- Open the Exchange admin center and go to Public folders > Public folder mailboxes.
- Select Add a public folder mailbox, enter a name, and select Add.
Create the mailbox with PowerShell
Connect to Exchange Online PowerShell, then run:
New-Mailbox -PublicFolder -Name MasterHierarchy
Microsoft identifies the first mailbox created as the primary hierarchy mailbox. To verify the organization’s root public-folder mailbox, run:
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Get-OrganizationConfig | Format-List RootPublicFolderMailbox
Create the public folder
Once the mailbox exists, create the folder in EAC or with Exchange Online PowerShell. EAC sets the folder name and path during creation; edit the folder afterward to configure additional settings. Do not include a backslash () in the folder name. Microsoft’s folder creation instructions cover both methods.
Create it in EAC
- Go to Public folders > Public folders.
- For a child folder, select its parent folder first. For a top-level folder, leave the parent unselected.
- Select Add a public folder, enter the name, and check the displayed path.
- Select Add.
Create it with PowerShell
Connect to Exchange Online PowerShell and use New-PublicFolder. This example creates a folder named Reports under Marketing2013:
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New-PublicFolder -Name Reports -Path \Marketing\2013
Choose an interface
| Interface | Best suited to | What to expect |
|---|---|---|
| EAC | Administrators who prefer a guided form | Choose the parent (if any), enter the name, review the path, and add the folder. |
| Exchange Online PowerShell | Administrators comfortable with commands or scripting repeatable tasks | Connect to Exchange Online, run the creation command, and use commands to verify the result. |
Either method creates the folder; permissions and any optional mail settings still need attention afterward.
Set permissions and verify the folder
New public folders inherit permissions from their parent by default. Microsoft recommends ensuring at least one user has the Owner permission level so someone can access the folder and create subfolders. Give other users only the access their work requires. See Microsoft’s public-folder permission instructions.
Refresh the EAC folder list to confirm the folder appears, or check it from PowerShell:
Get-PublicFolder -Identity \Marketing\2013\Reports | Format-List
To list public folders recursively, run:
Get-PublicFolder -Recurse
Mail-enable the folder only if it needs an email address
A public folder does not need to be mail-enabled for users to access it as a shared folder. Mail-enable it when people should be able to post by sending email to it; this makes settings such as email addresses and mail quotas available. Follow Microsoft’s mail-enable or disable instructions.
If people on the internet must be able to email the folder, granting that capability requires an additional permission: give the folder’s Anonymous account CreateItems. Microsoft’s PowerShell example is:
Add-PublicFolderClientPermission "Customer Feedback" -AccessRights CreateItems -User Anonymous
Quick Recap
Know the client limitations and service limit
- Outlook on the web: Users can add or remove public folders from Favorites and perform some item-level operations, but cannot create or delete public folders there. See Microsoft’s public-folder overview.
- Public-folder calendars: Microsoft’s Exchange Online calendar instructions require Outlook desktop to create a public-folder calendar and say public folders, including calendars, cannot be accessed from mobile devices. This is specific to calendar guidance; do not assume calendar setup steps apply to other folder types.
- Mailbox ceiling: Microsoft’s troubleshooting guidance, last updated June 25, 2025, states an Exchange Online tenant limit of 1,000 total public-folder mailboxes, including hierarchy-serving and non-hierarchy-serving mailboxes. Check current Microsoft limits before planning a large deployment. See the mailbox-limit guidance.
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