Public Folders in Exchange Online
Public Folders & Shared ResourcesPublic Folders in Exchange Online

Public Folders in Exchange Online

25 mins

Understanding the Concept

Public folders provide a way to collect, organize, and share information with other people in your organization. They use a hierarchical structure and can contain email, calendar, contacts, and other item types.

Exchange Online public folders use a modern architecture with content stored in public folder mailboxes. The hierarchy mailbox stores the public folder tree structure, while content mailboxes store the actual data.

Public folders can be mail-enabled, allowing external and internal users to send email directly to a public folder address. This is useful for team discussions, project communications, and departmental information sharing.

Key Points

Public folder hierarchy stored in dedicated hierarchy mailbox
Content distributed across multiple public folder mailboxes
Mail-enabled public folders receive email like regular mailboxes
Public folder permissions: Owner, Editor, Author, Reviewer
Maximum size per public folder mailbox: 100GB
Batch migration available for on-premises public folders to Exchange Online

Why This Matters

While modern collaboration tools like Teams are replacing some public folder use cases, many organizations still rely on public folders for shared calendars, contact lists, and organizational information. Understanding their management is essential for Exchange administrators.

Common Mistakes to Avoid

Creating too many public folder mailboxes without planning
Not setting proper permissions leading to unauthorized access
Ignoring public folder size limits causing mailbox splits

Interview Discussion Points

💡Explain the public folder architecture in Exchange Online
💡Compare public folders with modern alternatives (Teams, SharePoint)
💡Describe the process for migrating public folders from on-premises

MS-203 Exam Tips

📝Know public folder mailbox architecture (hierarchy vs content)
📝Understand public folder permission levels and inheritance
📝Be familiar with public folder migration batch requirements