A site mailboxe is functionally comprised of a SharePoint 2013 site membership (owners and members), shared storage through an Exchange 2013 mailbox for email messages, and a SharePoint 2013 site to store and share. Essentially, site mailboxes bring Exchange email and SharePoint documents together. For users, a site mailbox serves as a central filing cabinet for the project, providing a place to file project email and documents that can be accessed and edited only by site members. In addition, site mailboxes have a specified lifecycle and are optimized to be used for projects that have set start and end dates. To fully implement site mailboxes, end users must use Outlook 2013.

To learn more, see Site Mailboxes.

Public folders are designed for shared access and provide an easy and effective way to collect, organize, and share information with other people in your workgroup or organization.

Public folders organize content in a deep hierarchy that’s easy to browse. Users discover interesting and relevant content by browsing through branches of the hierarchy that are relevant to them. Users always see the full hierarchy in their Outlook folder view. Public folders are a great technology for distribution group archiving. A public folder can be mail-enabled and added as a member of the distribution group. Email sent to the distribution group is automatically added to the public folder for later reference. Public folders also provide simple document sharing and don’t require SharePoint Server 2013 to be installed in your organization. Finally, end users can use public folders with the following supported Outlook clients: Outlook 2007, Outlook 2010, and Outlook 2013.

To learn more, see Public Folders.

A shared mailbox is a mailbox that multiple designated users can access to read and send email messages and to share a common calendar. Shared mailboxes can provide a generic email address (such as info@contoso.com or sales@contoso.com) that customers can use to inquire about your company. If the shared mailbox has the Send As permission assigned when a delegated user responds to the email message, it can appear as though the mailbox (for example, sales@contoso.com) is responding, not the actual user.

To learn more, see Shared Mailboxes.

Groups (also called distribution groups) are a collection of two or more recipients that appears in the shared address book. When an email message is sent to a group, it’s received by all members of the group. Distribution groups can be organized by a particular discussion subject (such as “Dog Lovers”) or by users who share a common work structure that requires them to communicate frequently.

To learn more, see Recipients.

The following table gives you a quick glance at each of the collaboration features to help you decide which one to use.