How they differ
- Shared mailbox — a mailbox with its own address, inbox, sent items and calendar, opened by the people given access. Ideal for info@ or accounts@.
- Public folders — a tree of shared folders holding mail, contacts, calendars or posts, which can be permissioned folder by folder. Common in firms that built filing systems around them years ago.
Which to use today
For a new requirement, a shared mailbox — or in Microsoft 365, a group — is usually simpler. Public folders still make sense where an organisation already has a large, well-used structure that would be disruptive to replace.
The Outlook catch
Microsoft describes public folder support in the new Outlook for Windows as limited, and recommends classic Outlook for anyone who depends on public folders. Classic Outlook is supported until at least 2029. Our guide to the new Outlook has the detail.
If your business relies on public folders and is moving off its own Exchange server, hosted Exchange moves them across intact — see Exchange 2016 and 2019 end of support.