Office 365 Groups vs. Shared Mailboxes

Update (November 2022): Read Tony Redmond’s take on this topic five years on after Microsoft has given Outlook Groups a lot more functionality.

Comparing Shared Mailboxes and Office 365 Groups: the 2017 View

I was recently asked for my thoughts on using Office 365 Groups instead of shared mailboxes. Groups in Office 365 have many of the features that Exchange Online shared mailboxes do.

  • Multiple users can access a Group mailbox, just as they would a shared mailbox.
  • A Group mailbox can be used as a single point of email contact for a team or group of users, just as a shared mailbox can be.
  • Users can send-as or send-on-behalf of a Group mailbox, just as they would a shared mailbox.
  • Emails sent to Groups and shared mailboxes are preserved for historical reference, unless deleted by a user.

Office 365 Groups have additional features that shared mailboxes do not.

  • Users (members) can subscribe to receive a copy in their own mailbox of the emails sent to the Group mailbox, which makes Groups work in a similar manner to distribution lists.
  • Groups include additional collaboration apps and resources such as a SharePoint team site, OneNote notebook, Planner, and Teams.
  • Groups have a guest access model for external collaboration that shared mailboxes do not.
  • Groups have connectors for integrating other applications.

However, shared mailboxes have some capabilities that may make them more suitable to teams than Groups.

  • Shared mailboxes can have sub-folders in the mailbox, whereas Group mailboxes can’t.
  • Shared mailboxes have more granular permissions available than Groups do.

There is some demand for Group mailboxes to have sub-folders, as shown in the comments on this Uservoice suggestion. It’s quite common for teams that use a shared mailbox as an inbound communication channel to user sub-folder to sort or file away items that have been actioned. Although I prefer to recommend a proper ticketing/job management system instead, I understand that simpler scenarios don’t warrant setting up a whole separate system and that a shared mailbox with some sub-folders is quite sufficient.

The sub-folders capability is also a problem for anyone considering migrating public folders to Groups. If the public folders have a complex folder hierarchy that needs to be preserved, then you will basically lose that hierarchy due to the lack of sub-folders in Groups.

As it stands right now, the decision to go with Groups or shared mailboxes is a case of “it depends”. Work out which limitations are a showstopper for you, and which capabilities you need the most, and then make your decision based on that. Given the interest that Microsoft has in Groups adoption, perhaps we’ll see the sub-folders capabilities show up in the future.

Photo by Brendan Church on Unsplash

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About the Author

Paul Cunningham

Paul is a former Microsoft MVP for Office Apps and Services. He works as a consultant, writer, and trainer specializing in Office 365 and Exchange Server. Paul no longer writes for Practical365.com.

Comments

  1. Mason Y

    Can a group mailbox be transitioned to a shared mailbox? We have about 20 group mailboxes currently that receive emails from our clients. We are wanting to be able to email directly as that email address instead of as ourselves and CC’ing the group box to keep record of that email. I’m not sure if that makes sense..

    1. Avatar photo
      Tony Redmond

      No. But you can create a new shared mailbox and have it take over the email addresses of the group mailbox.

      1. Olivia

        Hi Tony,

        How do you go about doing that?

        1. Avatar photo
          Tony Redmond

          1. Create a new shared mailbox.
          2. Assign a new SMTP address to the group mailbox.
          3. Take the SMTP address previously assigned to the group mailbox and assign it to the shared mailbox.
          4. All email sent to the SMTP address will now be delivered to the shared mailbox.

          1. Isobel

            Hi Tony,

            I am experiencing similar issues. We have a group folder for our HR function, which currently has +1,900 emails in it. We are finding that the group folder does not offer the functionality we need to be able to collaborate – namely, we would like to be able to create sub-folders and categorise emails based on the team member that has actioned these.

            We were hoping to migrate the emails from the group folder over to a shared mailbox, however, from my research I have found that it is not as simple as it sounds. If I tried your option above, that being changing the group mailbox to a different SMTP and creating a new shared mailbox with the existing SMTP, would we be able to migrate the +1,900 emails over to the shared mailbox? If this is not possible (which I am almost certain it is not), would we still be able to access the group mailbox for history purposes?

            Thank you so much in advance!

          2. Avatar photo
            Tony Redmond

            Microsoft has announced (MC422161, August 29):

            With this release, users will have the ability to create folders and organize content inside Microsoft 365 Groups mailbox using Outlook on the web.

            Groups users will be able to create folders inside the Groups section in Outlook mail module. Users can move and copy messages across different folders inside of the Group. We are also releasing support for Rules inside Groups mailbox. With rules, users can automate the organization of incoming Groups mails. Once users have created folders, they will be able to view and access the deleted folder of the Group.

            The feature should be available in late September and might solve your problem.

  2. Lauren

    Thank you! Does anyone know the size limit of a group mailbox and if it can be expanded?

    I’d like to start using it to track emails our entire team should see by CCing the group email. Everyone else on the team (15 ppl) would do so as well and it would end up being a lot of emails since they are project-related emails. At least they will be searchable this way. I’m concerned that the Group Mailbox size may max out one day. Does anyone know the size limit and if it can be expanded? Maybe there would be an offloading solution rather than purchasing more space, like we move the emails and “archive” them somewhere. It’s likely they will be needed for reference at some point in the future.

    1. Avatar photo
      Tony Redmond

      I believe group mailboxes get a 50 GB quota (like shared mailboxes). At least, that’s what I see on my tenant. I was able to run Set-Mailbox to increase the quota to 100 GB, but I suspect this might cause some licensing issues. You could ask Microsoft…

      1. Teenu Daniel

        Yes , we need a license If the Shared mailbox size is over 50 GB. ( Ex: we just assigned a Microsoft 365 E3 license to the shared mailbox that increased the mailbox size to 100 GB)

  3. Mark

    Hi, so what should I do if I want these e-mail addresses (group or shared) to be used as some sort of sender from software that is doing automatic scans on a mailbox and sending replies? Does group or shared have SMTP to be able to send e-mails on its own?

  4. Sing

    Hi,
    Great thanks but need to know Is this article needs update in Aug 2021. If yes, do add last update date. It will help many.

  5. Matthew

    Paul,

    Great article. Any idea where the mail is stored? In Exchange Admin Center I don’t see a “Mailbox”. If I do not send mail to the users and keep it in the group, where is it stored?

  6. Sachin

    I want add sharemailbox id in Email group for some time, so that is possible
    because when I make a member sharmailboxID then i got error

    Please help

  7. Christine Lisi

    Can someone please answer these question on the subject? We have an Office 365 Group named help@blahblah.org set up. Users are subscribed to the group and whenever an email is sent from the public to the group, all users in the group receive the email.

    1. When the group users reply to the email using “From: help@blahblah.org” the response goes into THEIR Sent Items folder but not into the group mailbox. The only way their responses will go into the group mailbox is if we put the group email in the cc or bcc field. Is there another way around this?

    2. Do I have to add all of the members in the Send As and Send on Behalf permissions, or is subscribing all the user needs to do to receive the emails?

    Thank you!

    1. Hammaad

      I had this issue some years ago and I think (not entirely sure) you may have to create and add in the shared maibox via account settings > email > add, effectively it will require its own OST so it can save its send items in the sent folder, but I think this did cause issues with something but can’t remember exactly

    2. Mark

      For a shared mailbox, here is the command that retains a copy in the Sent folder of the shared mailbox

      set-mailbox -MessageCopyForSentAsEnabled $True
      set-mailbox -MessageCopyForSendOnBehalfEnabled $True

      I am not sure if this works similarly for group mailboxes.

  8. Zhenia

    Just wanted to say:
    probably more than 85% of my exchange/office365 knowledge has come from this generous man.
    Thank you Paul Cunningham.

  9. M

    We still use Public Folders, and are considering to use groups. Groups seem to be a usefull solution for us, but we run into some issues.

    I tried moving e-mail manually in OWA from a public (or personal) folder to a group, but am able to do this only one e-mail at a time. It should be possible with 100 e-mails at a time. It’s also not possible to drag e-mais to a group in Outlook.

    1. Dimarc67

      In the Outlook application (not OWA) you can move multiple messages at a time, but not directly to an O365 group. You first have to drag them to your mailbox (create a temp folder to hold them). Then you can drag them all at once from your mailbox to the O365 group.

  10. David

    Do Groups have the same Legal Hold capabilities?

  11. Jillian

    I can’t see how to auto-forward emails landing in a shared mailbox to more than ONE individual email address. I believe we can forward to multiple email addresses with Groups though. Is this possible with the shared mailbox and I’m just not seeing it? Thanks.

    1. Margaret Auld-Louie

      The way to forward to more than one email address with a shared mailbox is you set up a distribution group and you forward to the group. It’s a workaround but it’s what I’ve done for years due to the limitations of Exchange/O365.

  12. Kat

    I have noticed two features a shared mailbox calendar gives but an O365 group calendar doesn’t (hoping i will stand corrected and be provided with a way forward).

    1. You cannot export calendar items in csv format, whereas you can via outlook client on shared mailbox calendars, i don’t think you can for ical either but this may be a local setting we have not enabled. The best i can do is view appointments as a list and copy/paste out into excel and trim a little.

    2. You cannot create unique category colour tags for a group cal, you are only offered your own – these will be unique to each user andf therefore meaningless unless you are all 100% coordinated and have the same categories on your personal mailboxes. With shared mailbox calendars you can assign category colours to the mailbox and ll users of the mailbox are offered these.

  13. Jim Clelland

    We have 0365 with shared mailboxes but local Outlook is not pulling the shared mailbox into Outlook.
    Any ideas?
    All permissions are set and users can access the SMB via 365.

  14. Jason

    Can we access a group account/mailbox from an iOS device ( iPhone/iPad ) ??

    1. Jellman

      Yes via Outlook mobile app.

  15. David Slight

    Sub-folders is the missing feature holding me back ….

  16. Robin Morris

    Who took the design decision to have 2 very similar groupings 😉 and so have to read this to find out..

  17. Shawn

    Two questions.

    1.) Has anyone successfully migrated an existing ‘Shared Mailbox’ to a Microsoft Team site?

    2.) My user base typically utilizes a ‘Shared Mailboxes’ where the ‘Owners’ of the mailbox have permissions to both ‘Read’ and to ‘Send-as’ or reply with the Shared Mailbox name, where ‘Members’ can only read and process in-bound emails. How is this functionality emulated in either Microsoft Groups and/or Teams…or is this a use case for a Share Point Online site?

  18. Mike

    Hey Paul,
    Can you setup auto reply’s for Groups?

      1. Malvin Chitsa

        Are they any delivery restriction settings for Shared Mailboxes? I am trying to limit traffic to a particular mailbox but I do not see the option to change that. I do see it in Groups

  19. Stephen

    Hi, nice article, but another issue is that Office 365 Groups aren’t supported within Outlook 2013, so we will be sticking with Shared Mailboxes for the time being.

  20. Brent Webb

    This is a wonderful thread and article – I am currently moving my Exchange 2010 SP3 server to Office365 and I have one hurdle which I am not sure how to handle. Currently, we have a group of sales staff that pulls requests for quotes (RFQs) out of a group inbox (public folder that is mail-enabled). As they move them from the public folder to their own mailbox the other salespeople don’t see them anymore. So sales people will take their “stack” out of the “tray” and leave the remainder for other sales people. Obviously this public folder setup can be duplicated in Office 365, but it certainly isn’t what Public Folders are meant for.

    Would the Office365 Groups allow the same functionality?

    1. Avatar photo
      Paul Cunningham

      Groups will provide similar “shared mailbox” functionality as they currently have with a mail-enabled public folder. Groups come with a bunch of other useful stuff too, for example they get Teams, so the sales team can do persistent IM/chat amongst themselves. They also get a shared OneNote notebook and SharePoint site, so instead of working out of their own inboxes on RFQs they can move them into a SharePoint-based workflow and “work in the open” where everyone can see what’s going on and collaborate better.

  21. Zac

    You missed one thing shared folders can do that Groups can’t – have multiple email aliases.

  22. Ricky

    Does a group mailbox require a Office 365 license?

    We use shared mailboxes for just the calendar. Is the granular control still available for permissions on the calendar (I.E. Owner, Editor, etc.)?

    Thanks.

    1. Avatar photo
      Paul Cunningham

      Groups mailboxes don’t require a license.

      As I wrote in the post, shared mailboxes have granular permissions, Groups do not.

  23. Michael

    Hi Paul. Why not using public folders instat? I noticed people are moving from using Public Folders to Shared Mailboxes. But why? Office 365 groups seams to be more flexible again like Public Folders.

    And is there a way to use Office Groups with Outlook 2010? What benefits do groups have comapred to Public Folders?

    Cheers
    Michael

    1. Joe K

      More granular control of incoming email. If you want a single point of access, but want to react to individual emails (ie, build Rules) – there’s no way with Group Inboxes to setup rules.

      That, and the ability to partition the emails (sub folders).

    2. Dimarc67

      For years Microsoft has insisted that they have no intention of deprecating Public Folders, and they spent just enough resources to upgrade PF storage to use the same database platform as user mailboxes in order to deprecate the old storage scheme. At the same time, they’ve continued to provide minimal PF support and instead encourage adoption of Shared Mailboxes and O365 Groups whenever possible. Reliable backup solutions for O365 Public Folders are difficult to find or are too problematic to use for critical data protection. We have several hundred mail-enabled Public Folders for team messaging and distribution, but without good backup solutions we’re pushing away from them as best we can. Congrats, Microsoft. We lose.

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