Understanding Mailboxes in Office 365

Are you paying for a license for a Mailbox that should be Free?

Let’s take a look at the 5 different Mail accounts that Office 365 offers.

  • Mailbox – Requires a paid license
  • Group – Distribution Group – Free
  • Resource – Free
  • Contacts – Free
  • Shared – Free (Who Knew!?)

Mailbox – Most Common – Regular account for individual and provides an actual mailbox that you log into with its own Calendar and Resources. This type of account requires a paid license. This person/type of account can also have aliases. A very common example is a name change: [email protected] can have an alias of [email protected] or even [email protected].

Groups – AKA Distribution Groups. These are Free and can be useful for an organization as a whole. Instead of each user setting up individual groups in their contact list for [email protected] or [email protected], the distribution list can be set up in the Exchange Admin console and everyone would have access to it.

Resource – AKA Conference Room Mailbox or Equipment Mailbox. These are Free as well! This type of account is used for reserving and coordinating Rooms, Equipment, Other Resources (projectors, SCUBA gear, etc.). By including the Resource in a meeting request or calendar item, you are reserving the Resource for that time period. When you create your calendar event you can look at the Resource to check its availability.

Contacts – AKA External Contacts. Yup! These are free too… Contacts typically contain information about people or organizations that exist outside your Exchange organization. Mail contacts can appear in your organization’s shared address book and other address lists, and can be added as members to distribution groups. Each contact has an external email address, and all email messages that are sent to a contact are automatically forwarded to that address. Contacts are ideal for representing people external to your Exchange organization (in the shared address book) who don’t need access to any internal resources.

And my new favorite…

The infamous…

Shared – AKA Shared Mailbox. This is the most misunderstood and therefore under-utilized account that we’ve run across. It is not being utilized properly, if at all, by most organizations. Let’s say you have a generic email address on your website for [email protected] that you want 5 people in your organization to receive. Most often we see these being setup initially as Distribution Groups. When an email is sent to this address, it goes into the inbox of the 5 recipients, just like an email sent to them directly does. If they reply, it comes from the individual replying. Even if the user creates a rule to automatically move these to a subfolder in their inbox, it does not take long before this proves to be kludgy. What I find most Office 365 users doing next is biting the bullet and creating a paid account for [email protected] so it can have a mailbox. Then each of the five people, need to add the account to their Outlook client with the [email protected] username and the password for the sales account… Yada, Yada, Yada and before you know it, there are 5 more people that believe you to be pure evil. You know you’ve done this… we all have!

While I am sure that you love, love, love Microsoft,  don’t just give away the $$… This is what Shared Mailboxes are for. Plus they are a snap to administer with no end-user intervention required.

“Well that just seems too good to be true… What’s the catch??”

The limitations of Shared Mailboxes:

  • A Shared Mailbox does not require a license, but every user that accesses the Shared Mailbox must be assigned an Office 365 license
  • A Shared Mailbox cannot be accessed by users with an Exchange Online Kiosk license
  • A Shared Mailbox has a maximum size of 5 GB. Exceeding this limit will require as a minimum an Exchange Online license – see below for powershell script to make this easier to manage.
  • A Shared Mailbox can be used to store e-mails sent to and received by the Shared Mailbox
  • A Shared Mailbox can be used to store data migrated from on-premises Public Folders
  • A Shared Mailbox cannot be used to archive e-mails for individual users

There are limits to using a Shared Mailbox, if you want to stay within the free license. Not many are aware of this, but a Shared Mailbox cannot grow larger than 5GB, if it exceeds the 5GB limits it needs a license!

Set quota on your Shared Mailboxes

The best way to setup your Shared Mailboxes, is with a ‘Quota’.  This way you know they will not exceed the 5GB limit.

Here is how to setup the quota for a Shared Mailbox:

Set-Mailbox SharedMailboxName -ProhibitSendReceiveQuota 5GB -ProhibitSendQuota 4.75GB -IssueWarningQuota 4.5GB

If you want to set the quota on all your Shared Mailbox with one command, you can use this powershell command:

Get-Mailbox -ResultSize Unlimited -filter {RecipientTypeDetails -eq “SharedMailbox”} | Set-Mailbox -ProhibitSendReceiveQuota 5GB -ProhibitSendQuota 4.75GB -IssueWarningQuota 4.5GB

**the above scripts borrowed from Peter Schmidt at http://www.msdigest.net/2013/03/the-limits-of-shared-mailboxes-in-office-365/


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