Office 365 shared mailbox vs. public folders – what’s the difference?

[Update]: This article was updated on August 7, 2017.

Office 365 stands for collaboration. The very idea of work in the cloud stems from the need of data sharing any time we want and wherever we want. Therefore Microsoft developed features in Office 365 such as public folders and shared mailbox.

Group work: Office 365 shared mailbox vs. public folders

At first, they might look identical, with just different names – both, shared mailbox and public folders can store all types of Outlook items, both can receive and send emails, both can be accessed by many users simultaneously etc. However, when digging deeper into Office 365, differences start to emerge. Public folders are known from previous versions of Exchange. They appear in Outlook as a separate structure with the folder hierarchy supporting all types of items. They can also store files, documents etc. With Exchange 2013 and Office 365 they were redesigned slightly and now are stored in the same database as mailboxes.

Public folders

Public folders are best used as a project collaboration tool,  or data archiving entity. They can be mail enabled to receive message flow, serve as main appointment calendar or elaborate task management structure. Their main feature is its distribution – once the admin enables public folders they are automatically shown in users’ Outlooks.

Shared mailbox

Shared mailbox is a mailbox without a user. In other words – it is a mailbox to which many users have access and can send/receive messages. It serves best as a common contact mailbox, such as support team email or sales representatives general address. Therefore it is very often that each company department has its own shared mailbox with designated users or groups that have access to them.

Main differences are confronted in the table below.

Shared MailboxPublic Folders
Targeted number of usersSmall/MediumLarge
Who can access by defaultDesignated users/groupsAnyone in organization
Accessibility in OutlookAppears automatically as long as automapping is onOnce enabled – appears automatically in all
Outlook clients
Accessibility in OWANo, every user has to add a shared mailbox manuallyYes (limited to mail folders only, marked in
Outlook as favorites)
Accessibility from mobile devices Yes
(Learn how to open shared mailboxes on mobile devices)
(Possible only when using a third party product)
Storage limits in Office 36550GB50GB
LicensingNo license requiredRequires Exchange Online Plan 1 or Plan 2 licenses

Suggested reading

CodeTwo Email Signatures: company-wide email signatures for Office 365

Tools for Exchange Server

25 thoughts on “Office 365 shared mailbox vs. public folders – what’s the difference?

  1. I see that office 365 allows 1,000 public folders with a 50GB limit to the mailbox and a combined total of 50TB. Is each subfolder considered a public folder mailbox or is each main folder a mailbox that includes all of the subfolders?

    I’m planning to migrate about 50 users and their public folders to Office 465 in the next month.

    • Hi Will,
      Public folders are very similar to standard mailboxes in this manner – a subfolder is just a part of them. That said, when moving public folders, subfolders are not moved by default (for more information, take a look at public folder moves on TechNet).
      If you wanted to make the transition easier and seamless, you could use CodeTwo Office 365 Migration. The tool is a great migration helper, especially if there are public folders involved.

  2. My company is wanting to create an employee database that is updated by our HR Dept. Wanting a personal profile (name, birth, phone #, qualifications, certifications, etc.) we are currently using Office 365. Can anybody tell me what would be the best place on office 365 to create such a thing.

    • Hi ash,

      You can achieve this using a shared or public contacts folder – either way is good.

      Best regards,

    • Global Address List = The Microsoft Exchange Global Address List (GAL) is a list of all end users and their respective email addresses within an Exchange Server organization that uses Microsoft Outlook for email.

  3. We’ve been using O365 for some time now in our school and I would like to share out folders to my students to store their work on so I can evaluate it more efficiently. Is there a way to create a shortcut on the desktop or drives to the folder I setup for them and share? In the past I’d set up a folder on a server and share it out to them. It worked seamlessly and I was able to access their work at any time, as long as we were in the network.

    Any way to make this happen?


  4. Hi Deanne,
    I recently migrated a client away from onsite Exchange to O365. This includes a huge Public Folder structure. It’s working great accept for one major thing : searching. With the users on Outlook 2016 they are not able to search all the Public folders in one go. Sure they can search if they are in the correct folder but when mails have been stored somewhere in the Public Folders, the search turns up empty – only local folders in the user’s mailbox get searched.


    Thanks in advance.

  5. Hi Adam,

    Thank you for your response. Ive logged out and back in again but nothing has changed.

    I did change the folder listing using Control 6. This worked and I love the new layout, so I’m going to keep this but I still can’t see my public folder.

    Also the online version of outlook defaults to an email account that Microsoft creates which is [email protected]. Yet my business email account is the one I use locally on my laptop. When I created the public folder, I could see it immediately on the online version.

    I don’t know how it makes the link to the local copy, other than when I created my business account and logged in (online) for the first time, I used the installation option to download all the local apps. Then I opened outlook and created a mailbox for my business email account.

    I hope all this makes sense. Do you have any other ideas.

    Many thanks

  6. I am using Office Business 365. I installed a local copy on my laptop and have just about configured Outlook to work how I want it to.

    I then went on-line and logged in as admin to create a public folder. I wanted to be able to share emails etc with other users. I assumed that there might be some way of accessing this folder locally. But it appears that I can only access it using the Online version of outlook OWA.

    The online version of outlook doesnt contain all the functionality that the local copy does and I am happier in its environment. But I am right in thinking that sharing things can only be achieved with the OWA?

    • Hi Deanne,

      You may need to sign out and back into Windows, and restart Outlook to see the public folders.

      Please also make sure that you are using the Folder list view in Outlook by holding CTRL+6. Other view modes may not display public folders.

      Another thing you can try is granting the problem Outlook user permissions to the public folder (see step 3.):

      Let me know if this helps,

  7. We have an onsite exchange server and a public folder that’s mail enabled for each of our projects. This allows us to cc that public folder on all emails and easily keep a record of our conversations with clients. We have hundreds of these public folders.

    I understand there’s a limit of 100 mail enabled public folders in Office 365 and this is not enough for us so we can’t make the jump to O365.

    Does anyone have a suggestion for an alternative that will meet our needs or does anyone know if Microsoft is thinking about increasing the limit for mail enabled public folders?



  8. Hi all,

    I have a customer who has configured public folders in his office 365 exchange. He is able to receive emails in his public folders only from the people within his organization. I would like to check with you whether there is a way to make the public folders receive the emails from people outside their organization ?

    Thanks for anyone who can suggest me some ideas.


    • Hi yuva,

      First please try mail-disabling and then mail-enabling the folder via PowerShell using the below commands:

      Disable-MailPublicFolder -Identity [Public folder name of GUID]
      Enable-MailPublicFolder -Identity [Public folder name of GUID]

      To learn how to start a remote PowerShell session to Office 365 read this article.

      If the above doesn’t help, you may have to give Anonymous users rights to create items in the folder. You can do this using PowerShell:

      Add-PublicFolderClientPermission [Public folder name of GUID] -AccessRights CreateItems -User Anonymous

      For more see this TechNet article.

      Hope this helps,

  9. Hi,

    We’re looking at setting up Public Folders as project mailboxes, but think it might be too taxing on each project team’s 365 Outlook if it becomes part of their account.
    Each team member could have up to 10 project mail boxes on the go and at up to 50Gb each would make Outlook unusable.
    We looked at SharePoint as well, but the site mailboxes are limited to 5Gb, which is nowhere near enough.
    Anyone have any other suggestions ?


  10. Using O365 Business Premium. We have created 2 public folders that hold contact info. We want to sync these folders on company iPhones. The OWA app won’t support syncing public contact folders. Is there another 3rd party app that can accomplish this task?

  11. Hello Nicole,

    Yes, you can send messages “As” mail enabled public folder. Just make sure to assign “send as” permissions for your user to that specific public folder.

  12. Hi Jan,
    The problem might stem from the automapping feature, available in Office 365. In short it automatically opens a shared mailbox in Outlook when a user is granted with full access permissions to it. Therefore a shared mailbox should disappear from Outlook once those access rights are removed. Unfortunately I have noticed that this does not always work:
    Let me know if removing your access rights in Office 365 to that shared mailbox affected also your Outlook and removed it from there.

  13. Shared mailboxes works excellent, except for one thing:
    I have an Outlook 2010 version. Adding shared mailboxes works fine, but I’m not able to disconnect from them. In the account settings I only see my own mailaccount, in the “advanced folder” no additional mailboxes shows up.

    Anyone who knows how to disconnect to have it disappear from the folder tree?

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