Public Folders in Office 365 Exchange Online, a New Beginning

Exchange 2013 and Office 365 Exchange Online public folders have changed for the better.  Instead of being an aspect of email creates administrative headaches from a recovery and redundancy perspective.  They have become part of the traditional mailbox DAG design creating more of an acceptance by Exchange administrators.  Regardless of what was going on with the challenges surrounding the backend design users typically love them.  Public Folders provide a simple access to corporate or team shared information right within the Outlook or Outlook Web App interface. 

Considering the Limits

This article will focus on the Office 365 Enterprise plans.  There are Office 365 standalone plans available, but many of the limits are different.  If you are looking at a standalone plan be sure to check out this article before finalizing your Office 365 public folder decisions. https://technet.microsoft.com/en-us/library/exchange-online-limits.aspx

That being said, let’s focus on the Office 365 Enterprise plan and what Microsoft offers for your organizational public folders needs.  First up, they allow up to 50GB of public folder data per public folder mailbox up to 50.  This means that that the maximum total size your organization can use for all of your public folder mailboxes is 2.5 TB.  This 2.5 TB of data can hold up to 100,000 public folders.  Honestly, 2.5 TB of public folder data is quite significant and in most cases it is difficult to consider this a limitation, but I am sure there is an organization somewhere that will not be able to move to cloud-based public folders even with this amount of capacity. 

For public folders that are mail-enabled and can send/receive email here is a list of the limits you may need to consider.   When sending or receiving a message the size limit is 25 MB, which is really a quite reasonable limit; however, I have seen organizations that allow 40 and 50MB size messages.  The file attachment size limit is also, 25MB.  For both of these cases, this limit will encourage the need for alternative means of file transmittal such as FTP or other methods. 

Other considerations surrounding limits revolve around some of the measures that can protect our cloud-based email environment especially with mail-enabled public folders that receive external email.  One of many layers to protecting your environment from spam and mail-mailing worms/viruses is that Microsoft has implemented imposed mailing limits.  They are as follows for organizations that have an Office 365 Enterprise plan. 

The above limits and additional detail about Office 365 plans can be found in the Microsoft Technet library.  Here is a great resource with additional information on this topic. https://technet.microsoft.com/en-us/library/exchange-online-limits.aspx

Now Let’s Get Into the Real Details

Regardless of whether your organization will migrate its public folders to Exchange Online a primary public folder mailbox will be required to get started.  Also be aware that if the data in your public folders increases above the capacity allowed within public folder mailbox quotas, Microsoft automatically creates new public folder mailboxes.  https://technet.microsoft.com/en-US/library/ms.exch.eac.PublicFolderMailboxTabLearnMore(EXCHG.150).aspx?v=15.1.75.0&l=1&s=BPOS_S_E15_0_Slim

Additionally, in order to do public folder work within Exchange Online your administrator may need to verify that you have the appropriate permissions.  See the table below that highlights these requirements.  https://technet.microsoft.com/en-US/library/jj150556(v=exchg.150).aspx

Mail-enabled Public Folders

Organization Management or Recipient Management

Public folders in general

Organization Management or Public Folder Management

With that let’s get started with our first public folder mailbox!

After “public folders” has been selected there will be a notification as shown below that states that a public folder mailbox is required in order start any work with public folders.  See the image below.

Note:  This warning doesn’t prevent the creation of the mailbox, just a delay in the process for backend replication.

Next Step, Let’s Create Some Public Folders

Note:  The new folder will require new permissions or even may need to be mail-enabled.  We will first mail-enable the folder.

Public Folder Migrations

For migrations, while a primary public folder mailbox will still be required the steps for migrating public folders will be different.  Here are a couple of resources that will get you started with this process.

Summary

Before Exchange 2013 and Exchange Online, Public Folders have been referred to as the cockroaches of Exchange http://thoughtsofanidlemind.com/2011/02/04/exchange-2010-public-folders-part-1/, for me they have always been the “necessary evil”, and for some administrators just the thought of them makes them cringe.  But with public folder mailboxes, Microsoft is recreating the image of public folders.  It appears that this is a new beginning for public folders through a more reliable and supportable design.  Enjoy!