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Understanding Shared Mailboxes in Office 365 (updated)

Understanding Shared Mailboxes in Office 365 (updated)

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Many potential customers are asking about departmental mailboxes in Office 365. How can a department, a team etc share a mailbox, and does it involve a license?

Shared mailboxes in Office 365 Exchange Online allow a group of users to view and send e-mail from a common mailbox.

A shared mailbox:

  • doesn’t have a username and password, so users cannot log on to it directly. A user must sign in to his/her own mailbox and then open the shared mailbox using Send As permissions
  • don’t require a license, but each user that accesses a shared mailbox must be assigned to a subscription plan
  • cannot be accessed by users with Exchange Online Kiosk subscriptions
  • has a maximum size of 5 GB. Exceeding this limit will require an Exchange Online plan 1 subscription (see Note 1 below )
  • can be used to store emails sent to and received by the shared mailbox
  • can be used to store data migrated from on-premises public folders
  • cannot be used to archive e-mails for individual users

In Office 365 Exchange Online, shared mailboxes are created only via Remote PowerShell. See the article "A couple of tips for setting up Shared Mailboxes" - link for more details. Update March 26th 2012 - new GUI based tool for creating Shared Mailboxes

Note 1 -- From an Exchange perspective a shared mailbox is just a 5GB mailbox provisioned to a disabled user account (and delegated to a bunch of SG/Users). So when reaching the quota, mailbox will start receiving warning messages (10% prior to the quota) and then will start blocking mail sent from it (if “send as” as been granted and ‘from”  used) and finally it will refuse accepted new e-mail (with “mailbox is full” in the NDR).


See also

  • It is now possible to create a shared mailbox through the Office 365 web-based management portal.

  • I believe to open shared mailbox we need full access and not send as.

  • You need both full access and send as access

  • Is this limit (5GB) still valid?
    I've found a 50GB limit on this article

  • 10G is the limit for shared mailboxes

  • The limit has been increased to 50 GB if you are using Office 365 shared mail files.

  • When creating shared mailbox through powershell it does create a rather lengthy smtp entry. check with
    (get-mailbox ).EmailAddresses
    use that email to login (password can be reset through admin portal)
    when logged it allows for password change as it were non-shared mailbox. hope that helps

  • that command again is: (get-mailbox your_shared_mailbox).emailaddress

  • So it does have a password then?????????

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