These settings can be set at the following levels: We recommend that you set this as the same default that you use for regular mailboxes. Use the DefaultPublicFolderMovedItemRetention parameter on the Set-OrganizationConfig cmdlet. For example, if you have 20,000 users, you should have 10 public folder mailboxes. We recommend that you configure your hierarchy so that you have no more than 2,000 users per public folder mailbox. Number of user logons per public folder mailbox See Configure storage quotas for a mailbox. See Configure storage quotas for a mailbox.Īlthough public folder mailbox size can exceed 100 GB, it is not officially supported. This limit doesn't include subfolders beneath a single folder. The limit can be enforced with the MailboxMessagesPerFolderCountRecieveQuota parameter on the Set-Mailbox cmdlet. The limit can be enforced with the FolderHierarchyDepthReceiveQuota parameter on the Set-Mailbox cmdlet. The folder depth is the number levels of nested folders that can exist in one branch of a public folder tree. The limit can be enforced with the FolderHierarch圜hildrenCountReceiveQuota parameter on the Set-Mailbox cmdlet. For any deployment of 100,000 or more public folders, we recommend reading Considerations when deploying public folders.Īlthough you can create more than 1,000 sub-folders under a parent folder, it is not recommended. See Create a public folder mailbox.Īlthough you can create more than 1,000,000 public folders, it is not officially supported. Although you can create more than 1,000 public folder mailboxes, it is not officially supported. Itemġ,000 is the limit for Exchange Server 2016 CU2 or later. Looking for Exchange Online limits for Microsoft 365 or Office 365? See Exchange Online Limits.