Microsoft Exchange Server 2013 : Site mailboxes (part 3) - The life cycle of site mailboxes, Site mailbox provisioning policy

2. The life cycle of site mailboxes

Unique among Exchange mailbox types, you cannot create a site mailbox through EAC. Instead, you create a site mailbox as an app on a SharePoint team site. A site mailbox is treated like any other app such as a list that forms part of the functionality offered to team members. The logic driving this decision is that creating a site mailbox is done as part of the process to build the site to meet its business needs. If you think the site requires email to enhance the collaboration among team members, create a site mailbox. If not, don’t create a site mailbox.

If you’ve invested in setting up processes for creating SharePoint sites at the enterprise level, you can have those processes create site mailboxes at the same time that a classic SharePoint site is created. It’s also a good idea for the SharePoint administrators to determine whether new sites are subject to a life-cycle policy from the start to avoid many sites being created, used for a short time, and then remaining in an unused and unwanted state, gently withering away while occupying valuable resources. You might, for instance, decide that all sites will be removed by policy after three years to ensure that obsolete sites are removed after a reasonable time and that sites that are in active use are noted as such and site owners can take action to retain them.

Most site mailboxes are created by administrators adding the mailbox to a site after it has been created. Figure 3 shows the default set of options presented to an administrator after a new site is created. The option to add a site mailbox is to the far right and called Keep Email In Context. Clicking this icon starts the process of creating a site mailbox.

Figure 3. Adding a mailbox to a SharePoint site

Behind the scenes, SharePoint calls an EAC page to invoke the New-SiteMailbox cmdlet to create the new site mailbox and populate the properties of the mailbox with details such as mailbox ownership and access. Two distinct objects are created within Exchange. The first is the shared mailbox in which email items are stored; the second is the site mailbox object, which holds the properties that describe the connection between Exchange and SharePoint such as the URL that points to the SharePoint site. These objects can be examined with the Get-SiteMailbox cmdlet.

A certain amount of background processing and synchronization between Exchange and SharePoint has to occur before the site mailbox is fully ready for use. The work to create a site mailbox fully can take between 30 minutes and an hour to complete. The first user who can access the site mailbox is the person who creates the site. Shortly afterward, the access list for the site mailbox is updated with details of all the people who have access to the SharePoint site.

When everything is ready, SharePoint sends an email to the site members to tell them that the mailbox is available. Autodiscover notices the presence of the site mailbox and adds it to the set of resources listed in the payload provided to Outlook. This information enables Outlook 2013 to list the site mailbox as part of the resources available to the user. Those who do not use Outlook 2013 can access the site mailbox through a web browser.

Exchange identifies site mailboxes by setting their RecipientTypeDetails property to TeamMailbox (reflecting an older name for site mailboxes). You can scan for these mailboxes with the following command:

Get-Mailbox –Filter {RecipientTypeDetails –eq "TeamMailbox"} | Select Name

It is possible to create new site mailboxes directly from Outlook. However, some caution should be exercised here because previous experience with public folders proves that users often create repositories they use for a few days and then move on, never going near the repository again. It is probably better to have users go through a more structured approach to site mailbox creation until everyone happily knows how to take best advantage of this feature. But if you want to allow users to have free rein, you can do this by updating the Exchange organization configuration with a pointer to the SharePoint new site–creation page. For example, this URL works for an Office 365 tenant:

Set-OrganizationConfig –SiteMailboxCreationURL "https://contoso.sharepoint.com/_layouts/15/SelfServiceCreate.aspx?Context=Site"

After the organization configuration is updated, users can use the Create New Site Mailbox option in the menu that Outlook reveals when they click their account name in the Outlook navigation pane. The option redirects the user to the selected webpage.

At the other end of a site mailbox’s life cycle, when the site is no longer required, you do not remove the site mailbox from Exchange. Instead, you remove the site from SharePoint, and SharePoint makes an EWS call to Exchange to request the deletion of the site mailbox object.

When a site that includes a mailbox is removed from SharePoint by the life-cycle policy application, the site mailbox object is removed from Exchange, but the shared mailbox persists. In this instance, the mailbox is not removed immediately. Instead, it is tagged as obsolete by adding the “MDEL” prefix to its name by a job that runs daily. The mailbox is left in place and is not removed until an administrator deletes it by running the Remove-Mailbox or Remove-StoreMailbox cmdlet. (By comparison, site mailboxes hosted on Office 365 are deleted without the need for administrator intervention.) The mailboxes are left in place so their contents can be accessible for discovery searches for as long as necessary. Because the mailboxes are in place and not disabled, they also receive email.

It is possible to decouple the mailbox from the SharePoint site, which effectively leaves the mailbox in place with no connection to the site. You can do this by running the Set-SiteMailbox cmdlet. It’s not recommended to do this unless directed by support personnel, but for the record, an example command is:

Set-SiteMailbox –Identity "Project Alpha" –SharePointUrl $Null

Set-SiteMailboxProvisioningPolicy –Identity 'Default' –IssueWarningQuota 9.5GB –ProhibitSendReceiveQuota 10GB