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Mailbox Features

 

Applies to: Office 365, Exchange Online

Topic Last Modified: 2013-12-17

The information in this section describes the mailbox features of Exchange Online dedicated plans including mailbox types, the management of mailboxes, and features available to mail clients.

The maximum size of the mailbox for each Exchange Online Dedicated plan type is shown in the table in this section. The mailbox size for a user is represented in an extension attribute associated with the Active Directory object for the user. Your organization is responsible for populating the extension attribute with an allowed mailbox size value as described in the Mailbox Provisioning and Administration section.

When the amount of consumed space within a user mailbox reaches specific threshold levels, Exchange Online provides the following notifications to users:

  • Warning. The user receives an email warning when the mailbox is approaching the maximum size limit.

  • Prohibit Send. The user receives an email prohibit-send notification when the mailbox size limit is reached. The user cannot send new messages until enough email is deleted that the mailbox is below the size limit again

  • Prohibit Send/Receive. Exchange Online rejects any incoming mail when the mailbox size limit is reached, and sends a non-delivery report (NDR) to the sender. The sender has the option to try resending the mail later. To receive messages again, the user must delete email until the mailbox is below the size limit.

The following table summarizes mailbox sizes for Exchange Online Dedicated plans and the thresholds at which notifications and restrictions take effect.

 

Messaging Plan Mailbox Size Warning Prohibit Send Prohibit Send/Receive

Kiosk D Plan

Up to 2 GB

98% of set mailbox size

99% of set mailbox size

100% of set mailbox size

Plan 1D

Up to 50 GB

98% of set mailbox size

99% of set mailbox size

100% of set mailbox size

Plan 2D

Up to 50 GB

98% of set mailbox size

99% of set mailbox size

100% of set mailbox size

1 Any mailbox type configured to a size of 1GB or less will utilize a Warning value of 90%, Prohibit Send value of 95%, and a Prohibit Send/Receive value of 100%.

2 The maximum mailbox size supported by Office Outlook 2003 and Outlook 2007 is 20GB. A maximum mailbox size of 50GB is allowed with Outlook 2010 or Outlook 2013. However, a mailbox size in excess of 20GB has the potential to degrade the performance of the Outlook client and the replication of mailbox data between datacenters.

  • Identify and populate the defined extension attribute in your on-premises Active Directory to set mailbox size, plan type, features, and options (including resource and shared mailbox designation) as described in the Office 365 Dedicated and ITAR-support Plans Provisioning Handbook, available on the extranet site for existing customers.

Exchange Online offers special purpose mailbox types to support non-users (such as a conference room or shared equipment), multiple users, and for the retention of a mailbox for a deleted user account that was placed in a hold state for compliance purposes. Special purpose mailbox types are described below in greater detail.

The following characteristics apply to resource, shared, and inactive mailboxes:

 

Special Purpose mailbox Type Mailbox Size Warning Prohibit Send Prohibit Send/Receive

Resource

Up to 10 GB

98% of set mailbox size

99% of set mailbox size

100% of set mailbox size

Shared

Up to 10 GB

98% of set mailbox size

99% of set mailbox size

100% of set mailbox size

Inactive

No Size Limit 1

No Limit

No Limit

No Limit

1 See qualification requirements in the Limitations section of the Inactive Mailbox description.

Customer Responsibility

  • Resource, shared, and inactive mailboxes are provided at no charge if you apply specific provisioning parameters are applied as described in the Office 365 Dedicated and ITAR-support Plans Provisioning Handbook available on the extranet site for existing customers.

A resource mailbox is used for managing resources such as conference rooms and equipment. These mailboxes optionally can be configured to enable the Resource Booking Attendant (RBA), which automates scheduling of conference rooms and equipment based on resource availability. A resource mailbox that is RBA-enabled accepts, declines, or acknowledges messages from a meeting organizer. Exchange Online enables your organization to customize these responses through Outlook Web App.

You can also set booking policies or rules for your organization’s resource mailboxes. Examples include who can schedule a resource, when it can be scheduled, what meeting information is visible on the calendar of the resource, and the percentage of schedule conflicts allowed.

Customer Responsibility

  • Define all required resource mailbox objects in the on-premises Active Directory.

  • Define and manage Resource Booking Agent (RBA) settings through remote Windows PowerShell to support the resource mailboxes feature.

Limitations

  • Resource mailboxes of 10 GB in size are available to your organization at no extra charge only if specific provisioning instructions are followed per information provided by Microsoft.

  • A standard resource mailbox has a maximum size of 10 GB and does not require an Exchange Online license to be assigned to the resource mailbox. If a larger storage size is required, the resource mailbox must be upgraded to an Exchange Online Plan 1D or Exchange Online Plan 2D subscription license.

  • Resource mailboxes are subject to the same recipient limits and message rate limits as regular mailboxes. The limits are described in the Message Transport Management section.

  • A resource mailbox cannot be used to archive email for individual users. If an In-Place Archive is required for the resource mailbox, the resource mailbox must be either (a) an Exchange Online Plan 1D subscription with the Exchange Online Archiving add-on feature set subscription or (b) an Exchange Online Plan 2D subscription.

  • If In-Place Hold or Litigation Hold is required for a resource mailbox, the resource mailbox must be either (a) an Exchange Online Plan 1D subscription with the Exchange Online Archiving add-on feature set subscription or (b) an Exchange Online Plan 2D subscription.

A shared mailbox allows a group of users to view mail in, and send email from, a common mailbox (for example, info@contoso.com or sales@contoso.com). To access a shared mailbox, users must first be granted Send As or Full Access permissions to the mailbox. Users then sign into their own mailboxes to gain access to the shared mailbox. A shared mailbox is created by your organization by assigning a specific value in the designated SetMailboxType extension attribute for the mailbox object in the on-premises Active Directory.

Shared mailboxes have the following characteristics:

Limitations

  • Shared mailboxes of 10 GB in size are available to your organization at no extra charge only if specific provisioning instructions are followed per information provided by Microsoft.

  • Each shared mailbox has a maximum size of 10 GB and does not require an Exchange Online license to be assigned to the shared mailbox. If a larger storage size is required, the shared mailbox must be assigned an Exchange Online Plan 1D or Exchange Online Plan 2D subscription license.

  • If In-Place Hold or Litigation Hold is required for a shared mailbox, the shared mailbox requires a license and must be either (a) an Exchange Online Plan 1D subscription with the Exchange Online Archiving add-on feature set subscription or (b) an Exchange Online Plan 2D subscription.

  • A shared mailbox cannot be used to archive email for individual users. If an In-Place Archive is required for the shared mailbox, the shared mailbox must be either (a) an Exchange Online Plan 1D subscription with the Exchange Online Archiving add-on feature set subscription or (b) an Exchange Online Plan 2D subscription.

  • Each user that accesses a shared mailbox must be assigned a subscription plan license. The user cannot log on to a shared mailbox directly by using the shared mailbox account credentials. A user must first sign in to their own mailbox and then have appropriate folder or mailbox permissions to access the shared mailbox. Full Access permissions are required for users to open and access the shared mailbox. Send As permissions are required to send mail from the shared mailbox.

  • Shared mailboxes are subject to the same recipient limits and message rate limits as regular mailboxes. These limits are described in the Message Transport Management section.

  • Users with Exchange Online Kiosk D subscriptions cannot access shared mailboxes.

Before you delete an Office 365 user account that has been placed under In-Place Hold or Litigation Hold, you can convert the user’s mailbox to an inactive mailbox. This allows the contents of the mailbox to be preserved for compliance purposes for the duration of time that the user is on hold. Administrators, compliance officers, or record managers can use the eDiscovery feature in Exchange Online to access the contents of an inactive mailbox.

You are able to convert an active mailbox that was previously on a compliance hold to an inactive mailbox only if the user’s mailbox was previously assigned to one of the following Exchange Online plans: (a) Exchange Online Plan 2D or (b) Kiosk D or Plan 1D with the optional Exchange Online Archiving add-on feature. After an active mailbox on hold is converted to an inactive mailbox, you may reassign that user’s original plan type subscription to a new user account.

ImportantImportant:
  • If a compliance hold is not placed on a mailbox before the mailbox is deleted, the contents of the mailbox will not be preserved and therefore will not be discoverable. The mailbox can be recovered within 30 days of deletion as described in Deleted Mailbox Retention.

  • If a mailbox on a compliance hold needs to be retained as an inactive mailbox, specific provisioning instructions provided by Microsoft must be followed.

Customer Responsibility

  • Set compliance hold parameters on any mailbox that must be retained for compliance purposes to ensure the mailbox is not removed if account deletion action is invoked.

Limitations

  • An inactive mailbox can be created only for a Plan 2D mailbox or the Kiosk D or Plan 1D mailbox types that also have an Exchange Online Archiving add-on feature set subscription; no additional charge is incurred for the created inactive mailbox.

  • Users will not be able to log on to inactive mailboxes.

  • Inactive mailboxes will be hidden from the Global Address List.

  • Messages sent to inactive mailboxes will not be delivered and will result in non-delivery reports (NDRs) being returned to the sender The size of the inactive mailbox cannot exceed the size of the original active mailbox type.

In Exchange Online Dedicated plans, each object held in Active Directory must utilize an Exchange CustomAttribute (also known as Active Directory extension attribute) to hold mailbox size, plan type, feature settings, and other optional provisioning parameters. Information describing the use of the attribute can be found in the Office 365 Dedicated and ITAR-support Plans Provisioning Handbook available on the extranet site for existing customers. In addition to its primary role to keep the Active Directory of your on-premises environment synchronized with Office 365, the Microsoft Managed Solutions Services Provisioning Provider (MMSSPP) tool is used to assist with the provisioning of additional mailboxes and to set specific service features for each mailbox held in Exchange Online.

Two self-service mailbox administration options are available with Exchange Online Dedicated, (a) the menu driven Exchange Admin Center and (b) the command line oriented Windows PowerShell. For a summary of all administration tools, see Self-Service Administration.

Continuous replication of mailbox data to multiple servers provides data recovery capability in the event of a local messaging infrastructure failure. For large-scale failures, established Service Performance and Service Continuity Management processes are initiated.

Limitations

Exchange Online Dedicated retains a deleted mailbox for a 30-day period. Deleted mailboxes can be recovered by placing a service request with Microsoft Online Services Support or, under certain circumstances, automatically through the directory synchronization process. Changes to the default mailbox retention period can be requested through the configuration request process for Office 365 Dedicated plans.

Limitation

  • When the deleted mailbox retention period has passed for a deleted mailbox, the mailbox cannot be recovered.

Mailbox features provided to users in an on-premises Exchange Server environment are also available to Exchange Online clients. Many of the features are managed by your staff using the self-service capabilities provided in Exchange Online. Several features, as described below, involve engaging Microsoft to provide customization support.

Exchange Online provides a deleted item retention policy and the capability to provide single item recovery for messages deleted due to user initiated actions. When a user performs a soft delete of messages within their Deleted Items folder, the items are moved to the Deletions subfolder of the Recoverable Items folder associated with the user mailbox. The user can manually recover items from the Deletions subfolder within 30 days using Outlook or Outlook Web App. If the user accessed the Deletions subfolder and performed a hard delete of any of the items, the deleted items will be placed in the Purges subfolder for the balance of the 30-day period. Only an Exchange administrator can view and restore messages placed in the Purges subfolder.

Limitations

  • The default setting for the deleted item retention period is 30 days. A lower value can be set at the time of Exchange Online deployment or during the post-deployment period using the configuration request process for Office 365 Dedicated plans.

  • If In-Place Hold is enabled for a mailbox, none of the items in the Deletions subfolder are permanently deleted from Office 365 while the hold is in effect; the items are held in the system in a manner that is not visible to the mailbox owner.

NoteNote:
If the Recoverable Items folder for a mailbox placed on In-Place Hold reaches the 30 GB quota, contact Microsoft Online Services Support to increase the quota for the folder.

Custom address lists help users easily find contacts and resources contained within the Global Address List (GAL) of Exchange. In Exchange Online, customized views of the GAL can be created and each address list created can be available to users as an Outlook Address Book selection.

Customer Responsibility

  • Submit address lists creation requests using the configuration request process for Office 365 Dedicated plans.

Microsoft Responsibility

  • Implement requested customer changes to address lists.

Limitations

  • Customization of the Outlook Details Template is not permitted.

  • Address Book fields are limited to the Exchange custom attributes.

  • Address Lists are not added to the Offline Address Book (OAB).

User thumbnail photos placed in the on-premises Active Directory of your environment are propagated to the online Active Directory environment by the Office 365 provisioning tool. When an Outlook 2010 or Outlook 2010 client is used to interact with Exchange Online, the photo of the sender will be displayed in the message window.

Customer Responsibility

  • Provide solution for users or service desk staff to upload and modify thumbnail photos held within the on-premises Active Directory.

Microsoft Responsibility

  • Enable thumbnail photo synchronization flow from your organization’s on-premises Active Directory to Office 365 Active Directory.

Limitations

  • Photos will be displayed only in Outlook 2010 or Outlook 2010; support for Outlook Web App requires the High Availability infrastructure of Exchange Online Dedicated.

 
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