Problem Statement:

Can I grant Read Only Permission to a User's Mailbox (Cloud based service)?


  • Currently granting Read Permission to the entire Mailbox is not possible due to a Microsoft limitation.
  • The Access Rights 'ReadPermission' refers to the ability to read the Permission on the Mailbox and it doesn't grant any permission to the mailbox (including Read Only).
  • You can grant Read and manage delegation which is equivalent to Full Permission and it allows a delegate to open the mailbox and behave as the mailbox owner.

Read Permission is only usable for on-premise. It's not intended for end user's access.

To check other Mailbox Permission kindly refer to the KB article - How to Grant Access To Mailbox

You can however grant Read Permission at Folder Level using PowerShell or using Custom Action in CoreView.

Mailbox Folder Permission:

PowerShell cmdlet for Mailbox Folder level permission:

To add folder level permissions for users in mailboxes you can use PowerShell cmdlet - 


This cmdlet is available in on-premises Exchange and in the cloud-based service. Some parameters and settings may be exclusive to one environment or the other.


[-Identity] <MailboxFolderIdParameter>   
-AccessRights <MailboxFolderAccessRight[]>  
-User <MailboxFolderUserIdParameter>  
[-DomainController <Fqdn>]  
[-SendNotificationToUser <Boolean>]  
[-SharingPermissionFlags <MailboxFolderPermissionFlags>]  

Some Examples:

Add-MailboxFolderPermission -Identity\Marketing -User -AccessRights Owner

# This example grants the Owner role to Ed on the Marketing folder in Ayla's mailbox.
Add-MailboxFolderPermission -Identity\Calendar -User -AccessRights Editor -SharingPermissionFlags Delegate

# In Exchange Online, this example adds Julia as a calendar delegate to Ayla's mailbox, but without access to private items.
Add-MailboxFolderPermission -Identity\Calendar -User -AccessRights Editor -SharingPermissionFlags Delegate,CanViewPrivateItems

# In Exchange Online, this example adds Laura as a calendar delegate to Ayla's mailbox
with access to private items.

For more information on Mailbox Folder Permission kindly refer MSDN article:  Add-MailboxFolderPermission