Mailbox Types in Microsoft 365 and Their Uses

Microsoft 365 Mailbox Types

The Microsoft 365 platform offers organizations the tools they need to communicate and collaborate dynamically, but the set up can be overwhelming. If configured incorrectly, the types of resources offered, such as Mailbox Types and Groups, can create headaches down the line.In this article, we’ll go through the common account, mailbox, and resource types.  I will also briefly explain the best approaches to take when setting them up.

Breakdown of Mailbox Types

Microsoft 365 breaks things down into different types of accounts for different purposes. Some of them are much more simple than others.

  • Mailbox (License Required)
  • Group (Free)
  • Resource (Free)
  • Shared (Free)

 The best way to start is to configure a single user account.  Since a username and password are required to sign-in, these types of accounts should be assigned to actual human users. Any additional mailboxes, calendars, or resources can be created as shared accounts. Although, these reduce the security footprint of the organization. They do not include usernames and passwords.  Actual human users can only control the account, not sign-in.


Mailboxes can be set up for personal mail, devices, and programs. These do require a login username and password. This is the account you would want to configure for each person that needs access to any of the Microsoft 365 resources.Mailboxes can include multiple email address aliases to receive mail.  They can have access to other mailboxes and view shared calendars.  They can also forward mail to other mailboxes. This account type is considered a “full user account” because it is most commonly associated with a human user.

Distribution Groups

Historically, a Distribution Group is an email address without a mailbox. It forwards mail to one or more mailboxes users. Any mail sent to this group can be configured to arrive from both internal and external sources.

Microsoft 365 Groups

Microsoft 365 Groups differ from a Distribution Group by allowing additional types of information to be collected and shared. The 365 Groups can be members of Azure AD. They provide additional security settings and utilize Microsoft Teams for communication. These groups can store messages in a dedicated mailbox, instead of forwarding to other users. They can be accessed through mobile apps, and can also give specific users rights to send on someone else’s behalf. Additionally, users can be added to 365 Groups based on such attributes as department, location or title. Ultimately, these are for users who need more collaboration tools than a standard Distribution Group.

Room and Equipment Mailbox

These mailboxes reserve things such as conference rooms or company cars. Performing such an action can be as easy. Add the resource to a meeting in Outlook’s Scheduling Assistant to get a live view of availability.  Things such as capacity, locations, dedicated phone numbers, and custom email addresses can be set up for anything in your organization. Rooms and equipment can also be set for automatic or delegated approval from someone within the organization.

Shared Mailboxes

Shared Mailboxes are similar to full user mailboxes, with the exception of a username an password. This allows for multi-access to a mailbox, with its own calendar and folder list, without having to sign into a different account. The most common need we see is when a critical user has left an organization. Others need to act as that person, or gain access to historical information. By converting a full user account to a Shared Mailbox, the organization no longer has to license that individual to retain their mailbox capabilities.Often, companies need an email address shared by multiple people. Emails being sent to individual mailboxes can be difficult to keep organized. In this case, we would create a Shared Mailbox and give permissions to any pertinent user.

Full Permissions

The full access permission lets a user log into the Shared Mailbox and act as the owner of that mailbox. While logged in, the user can create calendar items, contacts and tasks. They can also read, view, delete and change email messages. However, users with full access permissions cannot send email from the shared mailbox unless they also have Send As permission.Full user accounts with full permissions to a Shared Mailbox can use Outlook Web App, or a desktop version of Outlook, to open that mailbox.Within a few minutes of set-up, users granted full permissions to a Shared Mailbox (or Group) will see it appear underneath their primary mailbox in the Outlook desktop application.To view a Shared Mailbox using Microsoft365’s Outlook web interface, follow Microsoft’s easy instructions:Have questions about Office 365 mailbox types? Or want to get more out of your existing Office 365 environment? Learn about our Managed Services here.

Jeff Hughes

Jeff Hughes

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