Up front, the most
important point to remember about site mailboxes is that they operate
on the principle of keeping the content where it belongs. In other
words, Exchange looks after email, and SharePoint takes care of
documents. This is an appropriate and intelligent division because
SharePoint is optimized for documents, and Exchange is not.
Public
folders make excellent repositories for email discussions, but they are
a pretty useless repository for document-based collaboration, such as
when a group of people works together to author a document or
presentation that will go through many editing cycles involving
multiple contributors. This can be done by using email, but it’s hard
to keep track of the many versions of documents that circulate as
message attachments unless someone is designated as the editor in
chief. It’s also possible to accomplish a collaborative authoring
process by using public folders as long as great care is exercised over
when different users access the document to update its content.
Unfortunately, humans are often not so good at exercising the necessary
care.
Site mailboxes are designed to fill the gap by using the
strengths of Exchange (for email) and SharePoint (for document
management). In effect, a site mailbox creates a virtual container that
includes a shared mailbox and the document libraries on a SharePoint
site. A SharePoint site is a website hosted by a SharePoint server that
is identified by a virtual URL. Each site can be configured with
different SharePoint components to create whatever functionality is
required by the site’s users. A site mailbox is an example of a
component that can be added to a SharePoint site; tasks, calendar, and
wiki apps are other examples.
The shared mailboxes created by the
site mailbox app are fully functional mailboxes that have email
addresses. The ability to accept email means that the site mailbox can
be used as a form of email archive for the project if you add the site
mailbox to any distribution groups used for project team
communications. Each mailbox contains default folders such as the Inbox
and Sync Issues, a folder that is particularly important because it
captures problems that occur when Exchange and SharePoint swap
information.
A synchronization process creates, populates, and
maintains folders in the mailbox to represent the contents of the
SharePoint document libraries that are associated with the site.
Appropriately, these folders use a document-centric view to display
their contents through Outlook rather than the conversation-centric
view normally used for email messages in other folders. You don’t
realize where the join exists between Exchange mailbox folders and the
folders populated through synchronization with SharePoint because
Outlook creates the impression that all the information in a site
mailbox is held in one place. The fact that two servers work together
to manage the site mailbox is immaterial to users. People never worried
that old-style public folders used a completely different database and
replication mechanism from Exchange mailboxes, so why should they worry
that some items are in an Exchange mailbox and some are in a SharePoint
site? The point is that they have access to the information they need
to perform a task.
Two
obvious dependencies leap off the page here. You need to deploy
SharePoint 2013 to support the sites, and you need Outlook 2013 to be
able to create the invisible join between mailboxes and sites. No other
client is currently capable of accessing site mailboxes. Companies
might well be considering a deployment of Outlook 2013 alongside
Exchange 2013 because this version of Outlook exposes all the
functionality in Exchange 2013, but a SharePoint deployment might
represent more of a barrier to overcome. Deploying SharePoint requires
additional investment in hardware, expertise, and software, and these
factors have to be taken into account in any discussion about site
mailboxes.
Nevertheless, assuming that all is well, that software
and hardware have been procured and deployed, and that SharePoint and
Exchange are both humming along like a well-tuned engine, the question
of functionality is the next topic of discussion.
1. How site mailboxes work
The steps required to implement site mailboxes are described
on TechNet and in many other web articles and do not need to be
repeated here. In summary, the deployment of site mailboxes depends on:
Exchange
2013 mailbox servers to host the shared mailboxes associated with the
SharePoint sites on which the site mailbox app is installed.
A
SharePoint 2013 farm (or standalone server) to host the SharePoint
sites that contain the document libraries and membership lists that are
synchronized with Exchange and combined with the shared mailboxes to
form site mailboxes. The SharePoint servers that host the sites and the
Exchange servers that host the mailboxes must be on the same premises
(on-premises or cloud), whereas the personal mailboxes of users can
function cross-premises. In other words, an on-premises Exchange user
can access site mailboxes that are stored in Office 365.
Outlook
2013 clients to present a single user interface to the site mailboxes
that include both the Exchange shared mailbox and the SharePoint
document libraries.
Exchange Web
Services (EWS) and SharePoint representational state transfer (REST)
application programming interfaces (APIs) to synchronize information
between Exchange and SharePoint.
A considerable
amount of work and cooperation is necessary between the Exchange and
SharePoint administrators to configure the products to work together
smoothly to enable the creation and operation of site mailboxes. Do not
anticipate that this work can be done without preparation.
SharePoint
communicates with Exchange using EWS, which means that you must
download and install EWS on your SharePoint servers. It is important
for a matching version of EWS to be installed on the SharePoint servers
so they can communicate with the mailbox servers. In other words, if
the mailbox servers run Exchange 2013 CU2, a matching version of EWS
should be installed on the SharePoint servers.
Membership
information (both users and owners) for the site mailbox is maintained
through SharePoint. Users are permitted access to site mailboxes by
being added to the membership list of the SharePoint site. Users have
to be added individually because gaining access through group
membership is not supported. In addition, users must have an Exchange
mailbox, and that mailbox has to be on an Exchange 2013 server before
they can use site mailboxes through Outlook. Users who have not yet
been moved to Exchange 2013 can still interact with site mailboxes by
opening the SharePoint site with a browser.
Behind the scenes,
SharePoint synchronizes the membership list with Exchange to grant
members full access rights to the shared mailbox. Like all other
operations affecting the life cycle of a site, provisioning and updates
for site membership is controlled from SharePoint, and Exchange does
not proactively query SharePoint to discover new site members. After
full access has been granted, Autodiscover adds the shared mailbox to
the list of resources available to Outlook the next time it queries
Exchange for this information, and Outlook opens the shared mailbox as
soon as the new resource becomes known.
Outlook 2013 Professional
Plus is the only client currently capable of displaying the site
mailbox data about document libraries that Exchange retrieves from
SharePoint. An Outlook Web App–like interface is available to the email
items in a site mailbox if you click the Mailbox link when accessing
the SharePoint site in a browser; this invokes an explicit logon to the
site mailbox. However, unlike Outlook, Outlook Web App does not include
site mailboxes in the set of available resources a user sees when he
accesses his personal mailbox, and there are no public plans to change
this situation. By comparison, Outlook considers a site mailbox like
any other resource available to a user—like a shared mailbox, archive,
or PST—so moving information into a site mailbox is as easy as dragging
an item from another Outlook resource. In effect, anyone who knows how
to work with Outlook can work with a site mailbox, which reduces the
cost of deployment and support.
Items can be added to the site
mailbox through SharePoint or Outlook by dragging and dropping items
into the folders in the document library within a site mailbox or the
other (regular) folders in the mailbox. It’s best to maximize the
relative strengths of Exchange and SharePoint by putting email items in
email folders and documents (such as those received as attachments to
messages) into document libraries. This approach means that you’ll be
able to use features such as threaded conversations for the messages
stored in the site mailbox’s Inbox and version control for the items
stored in the document library.
The
content stored in site mailboxes is indexed and discoverable by
eDiscovery searches. This is because Exchange 2013 shares the Search
Foundation technology with SharePoint. Email has long since been
indexed and discoverable; Exchange 2013 and SharePoint 2013 combine to
make the documents held in site mailboxes discoverable, too—a fact that
will surely bring joy to lawyers.
Site mailboxes are mail-enabled
objects and behave in the same way as mail-enabled public folders. In
other words, you can add a site mailbox as an addressee to a message,
and Exchange will route the message to the Inbox folder in the site
mailbox. Site mailboxes appear in address lists and can be hidden by
setting the HiddenFromAddressListsEnabled property to $True. This step
is usually taken to prevent users from including a site mailbox in
messages when the mailbox is being decommissioned. Messages can still
be sent to the site mailbox by using its Simple Mail Transfer Protocol
(SMTP) address.
Set-Mailbox –Identity 'Project Alpha' –GrantSendOnBehalfOf 'Paul Robichaux'
The Send As permission can also be assigned for a site mailbox. In this case, you use the Add-AdPermission cmdlet. For example:
Add-AdPermission –Identity 'Project Alpha' –ExtendedRights 'Send-As' –User 'Tony Redmond'
SharePoint
documents stored in site mailboxes remain in place when you add them as
attachments to messages. A link is added to the message to enable
recipients to access the content, but the documents stay in SharePoint
rather than being circulated as attachments. It makes perfect sense to
have a single definitive source for a document that’s intended as a
collaborative object as long as the recipients have sufficient network
connectivity to access the document when they need to. (The old
replication model for public folders, although derided by many, at
least had the singular advantage of making content available close to
users.)
Items stored in site mailboxes are not subject to
Exchange retention policies. All the information held in the site
remains under the control of the SharePoint information policy that
applies to the site. However, items in a site mailbox can be placed on
hold using the SharePoint eDiscovery Center.
The stub items that
represent the content of the document libraries can be synchronized
down to the client OST like the contents of other mailbox folders if
you select the Download Shared Folders check box on the Advanced tab of
your Outlook profile. If not, Outlook makes an online connection to the
shared mailbox when you want to work with its contents. Remember that
only the stub items are synchronized. The actual content of document
libraries always remains under SharePoint control. These stored
documents can be made available offline by synchronizing the site to
create a local copy of the document library on the PC. And, of course,
you can always download a local copy of an individual document from
SharePoint for use offline.
Synchronization between Exchange and SharePoint
Exchange
synchronizes with SharePoint by using the SharePoint REST API to fetch
the metadata used to display information about documents stored in the
site mailbox, including document title, author, last modified date,
checked-out status, and the user who last modified the item.
Information held in the documents library is synchronized and presented
alongside all the other folders in the site mailbox so that the data
from the two sources seems as though it originates from a common
repository. Items added to a document library through Outlook appear in
italics to indicate that the synchronization is not yet complete. In
other words, the item has been added to the Exchange mailbox but not
yet copied (or published) to SharePoint. After SharePoint has accepted
the item and stored it in the document library, the italics are removed
and not displayed by Outlook.
If you add more than one document
library to the SharePoint quick launch menu, Exchange will synchronize
the items from each library into a separate folder. As used in the
example discussed here, the default name for a document library on a
SharePoint site is Documents, and this is the folder name seen in
Outlook. The library could also be called Shared Documents, Project
Documents, or whatever other name you assign to it.
In general,
the synchronization process between Exchange and SharePoint is
reasonably fast, and new items added through one interface appear in
the other soon after they are added. If you add a new document library
through SharePoint, it will soon appear as a folder in Outlook.
Likewise, if you drag an item from Windows Explorer or File Explorer
and drop it into the Outlook folder, the item will be synchronized to
the SharePoint site within a few minutes. The same is true if you drag
and drop items from other Outlook folders into the site folder. You can
even create a subfolder for the site folder in Outlook, and it
synchronizes with SharePoint. Items placed in the subfolder will also
be synchronized with SharePoint. All of this works very well and makes
the site mailbox a very approachable repository for anyone who knows
how to work with Outlook. The sole downside is that you cannot drag
items out of any folder that is synchronized with SharePoint to Windows
Explorer (or File Explorer) or another Outlook folder; traffic is
unidirectional—into the folder. In addition, if you forward or
otherwise reference an item shored in a synchronized folder, the item
is not sent as an attachment. Instead, a link to the SharePoint site is
embedded in the message to allow the recipient to access the content by
clicking the link.
Synchronization is user-driven. In other
words, although information about a new site or document library or
changes to site membership need to be updated as quickly as possible,
information about the contents of a document library might not be so
time-critical, especially for document libraries that are not updated
very often. To make sure that Exchange and SharePoint remain
synchronized, a timer job runs on the Exchange mailbox servers every
six hours to make a request to SharePoint for information about new
members, documents, and so on. However, if a site is actively used
(documents or members are added), Exchange synchronizes with SharePoint
every five minutes, and if a site is open in either SharePoint or
Outlook, synchronization occurs every fifteen minutes even if items are
not added or otherwise updated.
Failure
of items to appear in a timely manner in either Exchange or SharePoint
is an indication that something is wrong with the synchronization
process. If this happens, you can check the last synchronization status
by selecting the site mailbox in Outlook. Right-click it and select
Site Mailbox Properties from the menu. This leads to a webpage (using
EAC) that shows information about the site mailbox, including a Sync
Status option. Here you’ll find the date and time of the last
successful synchronization together with any error messages plus
options to start synchronization. A useful Email Me Details option is
provided that requests Exchange to send you a message containing some
diagnostic information about the synchronization.
Information about
each document is stored as properties of a stub item in the folder used
to represent the document library in the site mailbox, including the
URL pointing to the item in SharePoint. If you examine the contents of
the Documents folder by using MFCMAPI, you can see the properties of
the SharePoint items that Exchange synchronizes. When Outlook connects
to the site mailbox, it retrieves data about email items from other
folders as usual and uses the stub items in the Documents folder to
construct the view of the information held in SharePoint.
Using
stub items enables Outlook to have faster display access to items in
the document library. When Outlook needs to retrieve content for an
item held in SharePoint, it passes the URL of the item to the native
application for the item. The application checks the Office Document
Cache to determine whether an offline copy exists or whether it needs
to retrieve a copy from SharePoint. A local copy might exist in the
PC’s local cache or because of a previous synchronization with the
document library to create an offline copy. When the correct location
for the content is determined, the application retrieves and opens the
item. As far as the application is concerned, it has received a request
to open and process content and does not care about its source.
Although it is usual to store mail messages in Exchange rather than in
a document library, you can move messages to a document library for
purposes such as marking the messages as immutable records. Messages
are stored in document libraries as .msg files, and Outlook opens these
items. Logically, if you open an item such as a Word document or a
PowerPoint presentation that is checked out to another user, you will
not be able to update the content.
Figure 1
shows how items in a site mailbox are accessed through Outlook 2013. In
this case, a site mailbox called Project Alpha is open. The Inbox,
Deleted Items, and Junk Email folders are stored in a mailbox database
that Exchange manages. The view of items in the Documents folder is
constructed from the stub items. The properties synchronized to the
stub items from SharePoint are sufficient to present an informative
view to the end user.
If
you run the Get-MailboxFolderStatistics cmdlet to report on information
held in a site mailbox, it reports the number of items and the size of
the items held in the Documents folder. The number of items is correct,
but the item size represents only the much smaller stub items that hold
the properties describing the real documents that are synchronized from
SharePoint.
Because Outlook provides the interface for site
mailboxes, some of the advanced document management features available
within SharePoint are not exposed. For example, you can’t see prior
versions of documents that are stored on the SharePoint site with
Outlook, and you can’t check out a document to reserve it against
editing by other users. These features are available by connecting to
the underlying SharePoint site with a browser. The easiest way to
access the underlying site for a document library is to select the
library in Outlook, right-click it, and select Open In Web Browser from
the menu. Figure 2
illustrates the situation after you have connected to the same Project
Alpha site as accessed through SharePoint through a browser. The same
items Outlook presents in the Documents folder are visible, but now
some additional options such as document checkout are available because
the web interface supports the options.
Accessing information about site mailboxes from Outlook
If
you right-click your mailbox name at the top of the folder list, you
see Manage All Site Mailboxes listed in the menu. Selecting this option
causes Outlook to make a call to EAC to display the My Site Mailboxes
page, listing the site mailboxes to which you have access. The list is
displayed on a webpage rather than by Outlook. The following fields are
shown:
Show In Outlook. Typically,
this check box is selected, meaning that Outlook should open the site
mailbox and display its contents. If you clear the box, the site
mailbox will be removed from the Outlook list of resources. Selecting
the box again restores matters, and the site mailbox will reappear.
Name. This is the name of the site mailbox.
Your Role. This will be Owner if you created the site mailbox or Contributor if the site mailbox has been shared with you.
Active. This is a flag showing whether the site is still active.
The
details pane for the selected site shows the SMTP address of the site
mailbox, the URL to the SharePoint site, the list of owners, and the
number of members. If you click a site, EAC retrieves and displays
status data for the site. You can discover the current synchronization
status and the list of users who have access to the site here.
Site mailboxes and Office 365
Site mailboxes are also available in many of the
Office 365 plans Microsoft offers. Office 365 tenants might find it
easier to adopt site mailboxes, if only because Microsoft takes care of
all the heavy lifting to deploy and manage Exchange Online and
SharePoint Online. All the tenant has to do before she can use site
mailboxes is make sure that she uses Outlook 2013. In fact, the easiest
way to review the functionality of site mailboxes and assess whether
they offer value to your company is to take out a 30-day trial for an
Office 365 plan that includes site mailbox functionality and use that
tenant domain to test how site mailboxes work.
