Enabling access to legacy public folders from Exchange Online

This topic - although there is a lot of information available; can be quite overwhelming since there are so many potential scenarios and the sheer amount of documentation available.

This post is a quick summary of the steps I performed to provide access to Exchange Online users (who were part of a hybrid Exchange setup) to an on-premis Exchange 2010 (SP3) organization.

In my experience after I completed the initial hybrid wizard when first setting up the hybrid environment I found that users within Exchange Online did not have any access to public folders which were located on the on-premis site - in this particular setup public folders must be located either on-premis or on our Exchange Online tenant.

To begin we should firstly create a proxy mailbox that will allow you to access legacy public folders from office 365:

(Step 2) https://technet.microsoft.com/en-gb/library/dn249373(v=exchg.150).aspx

Then synchronize our mail enabled public folders (you don't need to do this for normal public folders):

(Step 3) https://technet.microsoft.com/en-gb/library/dn249373(v=exchg.150).aspx

We should then ensure that the mailboxes are available remotely from Office 365:

Set-OrganizationConfig -PublicFoldersEnabled Remote -RemotePublicFolderMailboxes PFMailbox

ensure that the directory synchronization is up to date:

Start-ADSyncSyncCycle -PolicyType Delta

and then finally set a default public folder mailbox for our office 365 users e.g.:

$session = New-PSSession -ConfigurationName:Microsoft.Exchange -Authentication:Basic -ConnectionUri:https://ps.outlook.com/powershell -AllowRedirection:$true -Credential:(Get-Credential)

Import-PSSession $session

Set-Mailbox –Identity [email protected] –defaultpublicfoldermailbox PFMailbox

Note: It took a good hour for the public folders to appear on my Outlook client (even after I forced the directory synchronization) - so be patient!