Shared Mailbox Limitations in Office 365

A shared mailbox in office 365 is:

• Free and do not require a license, but every user that accesses the Shared Mailbox must be assigned an Office 365 license.
• Cannot be accessed by users with Exchange Online Kiosk license.
• 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.
• Each shared mailbox can be a maximum size of 50GB but shared mailboxes over 50GB in size need to be licensed.
• A Shared mailbox doesn’t have a username and password and users cannot log into it directly. A user must sign in to his/her own mailbox and then open the shared mailbox using permissions.

Shared mailboxes aren’t primarily associated with individual users and are generally configured to allow access by multiple users e.g. departmental users, Sales team, HR etc.

• Cannot be used to archive emails from a user.
• Cannot be used for Journaling.
• Cannot be accessed using ActiveSync clients.
• Doesn’t support Unified Messaging feature.
• Cannot be accessed using Outlook client. To access a shared mailbox on outlook client, you need to first configure a user mailbox that has access to shared mailbox.
• Active Directory user associated with a shared mailbox is always a disabled user account.

http://msexperttalk.com/understanding-shared-mailbox-limitations-office-365/