Exchange Online - Users Unable to access Public mailbox

Issue: Office 365 users cannot access newly created public folder

Resolution: 

Opened Windows PowerShell as an admin and ran command below for each public folder in order to grant permissions for external senders to send to the folders.

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Set-ExecutionPolicy Unrestricted -Force

connect-exchangeonline

Add-PublicFolderClientPermission "\Folder Name" -AccessRights CreateItems -User Anonymous
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• Set domain (yourdomain.com) to use Internal Relay in the EAC.
  
  
  • Ran PowerShell command below for each public folder to remove the email address policy.
  
  

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Set-MailPublicFolder -Identity "\Folder Name" -EmailAddressPolicyEnabled $False
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• Edit each public folder in the EAC and set the secondary proxy address with domain (yourdomain.com) to be used as the reply to address
  
  Mail-enable or mail-disable a public folder
  
  https://docs.microsoft.com/en-us/exchange/collaboration/public-folders/mail-enable-or-disable?view=exchserver-2019
  
  Use favorite public folders in Outlook on the web
  
  https://docs.microsoft.com/en-us/exchange/collaboration-exo/public-folders/use-favorite-public-folders