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Limits for public folders

 

Applies to: Exchange Server 2013

Topic Last Modified: 2014-08-25

In Exchange Server 2013, we moved public folders from a traditional database architecture to a mailbox architecture. This shift allows public folders to benefit from things such as the resiliency of a Database Availability Group (DAG) and other mailbox enhancements made over the years. However, there are new limits and performance concerns that should be taken into account. In this document we provide some high level guidance for configuration options you have that could affect public folder performance and connectivity.

The following table lists the limits for public folders in on-premises Exchange Server 2013. Unless the limits are specifically stated as recommended, the values listed here are the supported limits for public folders.

ImportantImportant:
Looking for Exchange Online limits for Office 365? See Exchange Online Limits.

 

Item Limits Notes

Total number of public folder mailboxes

100

Although you can create more than 100 public folder mailboxes, it isn’t supported. Create a public folder mailbox

Total public folders in hierarchy

100,000

Although you can create more than 100,000 public folders, it isn’t supported. Create a public folder

Sub-folders under the parent folder

1,000

While you can create more than 1,000 sub-folders under a parent folder, we don't recommend that you do so.

FolderHierarchyChildrenCountReceiveQuota parameter on the Set-Mailbox cmdlet.

Folder depth

300

The folder depth is the number levels of nested folders that can exist in one branch of a public folder tree. FolderHierarchyDepthRecieveQuota parameter on the Set-Mailbox cmdlet.

Maximum messages per public folder

1 million

MailboxMessagesPerFolderCountRecieveQuota parameter on the Set-Mailbox cmdlet.

Maximum individual public folder size

10 GB

This limit doesn’t include subfolders beneath a single folder.

Configure storage quotas for a mailbox

Public folder mailbox size

100 GB

Configure storage quotas for a mailbox

Number of user logons per public folder mailbox

2,000 concurrent user logons

We recommend that you configure your hierarchy so that you have no more than 2,000 users per public folder mailbox. For example, if you have 20,000 users, you should have 10 public folder mailboxes.

Moved item retention

14 days recommended

Use the DefaultPublicFolderMovedItemRetention parameter on the Set-OrganizationConfig cmdlet.

Age limit

We recommend that you set this as the same default that you use for regular mailboxes.

These settings can be set at the following levels:

  • Organizational level: DefaultPublicFolderAgeLimit parameter on the Set-OrganizationConfig cmdlet.

  • Mailbox level: AgeLimit parameter on the Set-Mailbox cmdlet.

  • Folder level: AgeLimit parameter on the Set-PublicFolder cmdlet.

Deleted item retention

We recommend that you set this as the same default that you use for regular mailboxes.

These settings can be set at the following levels:

  • Organizational level: DefaultPublicFolderMovedItemRetention parameter on the Set-OrganizationConfig cmdlet.

  • Mailbox level: RetainDeletedItemsFor on the Set-Mailbox cmdlet.

  • Folder level: RetainDeleteItemsFor parameter on the Set-PublicFolder cmdlet.

 
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