Give Mailbox Permissions to Another User in Office 365 – 3 Ways

Every once in a while, business users of Outlook may want to give mailbox permissions to another user in Office 365. Perhaps they are going on a long leave or wish to lower the burden of continuous communication. The reason may vary, but the steps remain the same. Let us start off with deflation access on the new Outlook client.

Giving Mailbox Permissions in the New Outlook Client (Owner)

This process allows you to delegate access to the required Office 365 mailbox effectively.

• Step 1. Open the new Outlook Client on your machine.
• Step 2. Hover the cursor over the account and click on the three horizontal dots that appear.

Step 2.1. If you want to share at the folder level, click on the arrow next to the account name and expand the folders. Then choose the mailbox folder you want to share.

• Step 3. From the flyout menu, choose Sharing and permissions.
• Step 4. Click the plus icon in the Permissions section at the top of the information store box.
• Step 5. Within the Add permissions pop-up, search bar, type in a name (you can only put one name here).
• Step 6. Press Add.
• Step 7. Toggle the Permission level dropdown and select eight preset levels from a list.
• You can see that options vary from owner to contributor in decreasing order of privilege; select them as per the requirement. Plus, you can also set your options and create a custom role.
• Step 8. Once done, click OK.

Accepting Office 365 Delegate Access to Mailboxes in New Outlook Client (Recipient)

These steps are to be performed by the recipient.

• Step 1. Launch the Outlook Client on your machine.
• Step 2. Hover the cursor over the account and click on the three horizontal dots that appear.
• Step 3. In the flyout menu, click Add shared folder or mailbox.
• Step 4. Type the name of the account sharing mailbox permissions with you (here, you can only put one name here).
• Step 5. Press Add.
• Step 6. Expand the Shared with me section.
• Step 7. Look for the new mailbox.

This completes the steps for the recipient to access the delegated content using the new client, demonstrating delegate mailbox access in Office 365. Next up, we have the steps for the classic client.

How to Delegate Access to Mailbox in Office 365 Using Classic Client

In Outlook Classic, the steps are as follows to manage M365 mailbox permissions:

• Step 1. Start up an instance of the Outlook Classic client.
• Step 2. Select any account or folder from the left pane and right-click on it.
• Step 3. Choose the Folder permissions option in the flyout if it is an account.
• Step 3.1. Suppose it’s a folder, select the Properties option.
• Step 4. For those only sharing a folder, switch to the Permissions tab of the properties pop-up.
• Step 5. In the Permissions section, click on Add… to give mailbox permissions to another user in Office 365.
• Step 6. Within the Add users window, you can use the search bar to find an exact recipient account or scroll up/down the user list to look for the accounts manually.
• Step 7. Once selected, the Add the account button should appear in the bar next to the button.
• Step 8. After you have added all the delegates, click OK.
• Step 9. Back in the main permissions page, all the added accounts are selected already. You may continue as it is, or deselect and reselect one at a time.
• Step 10. Toggle the Permission level dropdown and select eight preset levels from a list.
  You can see that options vary from owner to contributor in decreasing order of privilege; select them as per the requirement. If your permission options don’t match any of the preset categories, Outlook Classic assigns a custom role to your selection, potentially providing read-only access to the mailbox in Office 365.
• Step 11. Once selections are done, click Apply(repeat role application for each account separately). After you finish, press OK, as it closes the permissions menu, and you must redo many steps again.

Recipient action happens automatically. Next admin-side delegation tactics.

Administering Exchange Online Mailbox Permissions via GUI

Admin side user mailbox delegation in Exchange Online Mailbox Permissions offers a centralized way to manage access. This is crucial before you decide to archive former employee mailboxes in Office 365.

• Step 1. Login https://admin.exchange.microsoft.com/
• Step 2. Search and select a user mailbox with an active license.
• Step 3. In the right pane, switch to the Delegation tab.
• Step 4. Edit any one of the following permissions:
  • Send as
  • Send on behalf
  • Read and Manage(Full Access Permissions Office 365)
• Step 5. Press the + Add members button.
• Step 6. Mark the box next to one or more members(make sure the accounts you are marking are themselves users with active licenses.
• Step 7. Press Save.
• Step 8. Confirm.

It takes approximately 5 minutes for the changes to reflect on both accounts. This covers managing O365 full access permissions. Moreover, admins are not limited to the GUI; they can perform a highly controlled deletion via PowerShell. Let’s see how.

Managing O365 Mailbox Permissions with PowerShell: Connecting & Viewing

If you believe the GUI is slow and clumsy, there is an alternative to do the same in PowerShell for O365 mailbox permissions.
Step 1. Connect to Exchange Online PowerShell: Open PowerShell and connect to Exchange Online.

Connect-ExchangeOnline

Step 2. You will be prompted to sign in with your administrator credentials.

Step 3. Start Viewing Permissions: To see existing permissions on a mailbox or folder:

Get Full Access, Send As, and Send On Behalf permissions for a mailbox

Get-MailboxPermission -Identity "MailboxOwnerEmailAddress"

Get Folder permissions for a specific folder (e.g., Inbox)

Get-MailboxFolderPermission -Identity "MailboxOwnerEmailAddress:\Inbox"

Replace “MailboxOwnerEmailAddress” with the user’s email address. For folder permissions, append :\FolderName. You can use Get-MailboxFolderStatistics -Identity “MailboxOwnerEmailAddress” to find folder paths.

Adding Delegate Mailbox Access to Office 365 using PowerShell

This section details how to office 365 grant access to mailbox via PowerShell cmdlets.

Step 4. Allow/Add Permissions:
Full Access:

Add-MailboxPermission -Identity "MailboxOwnerEmailAddress" -User "DelegateEmailAddress" -AccessRights FullAccess -InheritanceType All

InheritanceType All ensures the permission applies to subfolders as well.

Send As:

Add-RecipientPermission -Identity "MailboxOwnerEmailAddress" -Trustee "DelegateEmailAddress" -AccessRights SendAs

It is managed using Add-RecipientPermission.

Send On Behalf:

Set-Mailbox -Identity "MailboxOwnerEmailAddress" -GrantSendOnBehalfTo "DelegateEmailAddress"

This command adds the delegate to the list. You might need to get the current list first, add the new user, and then set the full list to add multiple delegates.
Folder Permissions: (e.g., giving Editor access to the Inbox), useful for granting read-only access to the mailbox Office 365 via PowerShell, or other folder-specific roles:

Add-MailboxFolderPermission -Identity "MailboxOwnerEmailAddress:\Inbox" -User "DelegateEmailAddress" -AccessRights Editor

Replace :\Inbox with the correct folder path and Editor with the desired permission level (e.g., Reviewer, Owner, Contributor, None).

Removing O365 Delegate Access to Mailbox via PowerShell

To revoke O365 delegate access to the mailbox, you can use the following PowerShell commands.
Revoke/Remove Permissions:
Full Access:

Remove-MailboxPermission -Identity "MailboxOwnerEmailAddress" -User "DelegateEmailAddress" -AccessRights FullAccess -InheritanceType All -Confirm:$false

-Confirm:

falseskipstheconfirmationprompt.

SendAs:

Remove-RecipientPermission -Identity "MailboxOwnerEmailAddress" -Trustee "DelegateEmailAddress" -AccessRights SendAs -Confirm:$false

Send On Behalf:

Set-Mailbox -Identity "MailboxOwnerEmailAddress" -GrantSendOnBehalfTo @{Remove="DelegateEmailAddress"}

Using @{Remove=…} is the standard way to remove a single entry from this multi-valued property.
Folder Permissions: (Removes all folder permissions for that user on that specific folder)

Remove-MailboxFolderPermission -Identity "MailboxOwnerEmailAddress:\Inbox" -User "DelegateEmailAddress" -Confirm:$false

You cannot selectively remove just one permission level if multiple were granted via Add-MailboxFolderPermission; Remove-MailboxFolderPermission removes the user’s entry entirely for that folder. To change permissions, you would use Set-MailboxFolderPermission.

Accessing Delegated Mailbox Access Office 365 on Mobile

Conditions and Process of achieving Mailbox delegation on Mobile. The Outlook mobile app (iOS and Android) generally does NOT allow a user (the owner/sender) to initiate or grant most mailbox sharing permissions directly from the app.

You must use the Outlook Web, the new Outlook Client, or Classic Outlook Client to perform the delegation. Otherwise, contact the admin and ask them to set the permissions.

Regardless of the approach, the recipient can use the app on their mobile device to get mailbox access. Here are the steps:

• Step 1. Open the Outlook app on your iOS or Android device.
• Step 2. Then, Sign in with your primary Microsoft 365 account( It should be the same one with access to the delegated mailbox).
• Step 3. Tap on your profile picture or initial in the top left corner of the screen (this opens the account menu). On some versions, it might be a hamburger menu (three horizontal lines).
• Step 4. Then, in the menu that appears, tap the “Add Account” button. This button often looks like an envelope with a plus sign (+) or is labelled “Add Account”.
• Step 5. Tap “Add a Shared Mailbox” from the options that pop up.
• Step 6. If you have multiple accounts already added, the app might ask you to select the primary account with permissions to the shared mailbox. Select your main work/school email address.
• Step 7. Enter the email address of the shared mailbox or the delegated user’s mailbox you want to access.
• Step 8. Tap “Add Shared Mailbox” or a similar confirmation button.
• Step 9. The Outlook app will then verify your permissions. If successful, the shared or delegated mailbox will be added to your list of accounts in the left navigation pane.

Conclusion

In this blog, we taught readers how to give Office 365 mailbox permissions to another user in Office 365. We also gave instructions on self-managed delegation, admin-managed delegation, and the steps to accept the delegation on mobile. Plus, if you are an admin and want to preserve the email communication data, you can use the best-in-class Office 365 backup tool from SysTools.

For collaborative projects, you might also want to create a knowledge base in SharePoint.