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5.9. How to grant Exchange and Outlook mailbox permissions in Office 365

Choose the appropriate option depending on whether the mailbox is shared with you or you are a delegate for another user's mailbox.

Notes:

When you use any of these methods, the shared mailbox account is added as an option in the From field when you compose emails. This lets you select the account in the From field regardless of whether you have permissions to send from this account. If you do not have "Send As" or "Send On Behalf of" permissions for the account, email from the account will not be sent.
Outlook for Mac does not support Auto-mapping of shared mailboxes.

A folder is shared with you

If another user has shared an inbox, primary calendar folder, or primary contact folder with you, use this method to open the user's folder.

To open the shared folder:

On the File menu, click Open.
Click Other User's Folder.

You are a delegate for another user's mailbox

Use this method if you are a delegate for another user's mailbox or when you have permissions to several folders in a shared mailbox. You can also use this method when you have full access permissions to a mailbox.

To open the shared mailbox:

On the Tools menu, click Accounts > Advanced > Delegates.
Add the mailbox under Open these additional mailboxes

Note: If you have permissions to custom folders in the mailbox but not to the top-level mailbox folder, the custom folders will not appear in the folder list. Only default folders that you have permissions to, such as Inbox, Sent Items, Deleted Items, and Calendar, will appear in the folder list without top-level mailbox folder permissions.

Delegates settings in account advanced settings

You have full access permissions to a shared mailbox

When you have Full Access permission to a shared mailbox—that is, Full Access permission of a mailbox set up through Exchange Admin Center (EAC)—you can add the shared mailbox with your own credentials.

To open the shared mailbox:

On the Tools menu, click Accounts.
Click the Plus Sign to add an additional Exchange account.
In the E-mail address field, enter the email address of the shared mailbox.
Under Authentication, enter your own credentials.

Checking the setting Sync shared mailbox will allow Outlook to synchronize the shared mailbox without requiring the user to click Send/Receive. This setting was added in version 16.13.411. Enabling this setting is highly recommended for users who use their own credentials to access a shared mailbox.

Sync a shared mailbox

Permissions for shared folders and mailboxes

The following table summarizes the permissions options that may be available for a shared folder or mailbox, and the best method for opening the shared folder or mailbox based on the corresponding permission.

Level of permission to shared folder or shared mailbox	Method to open shared folder or mailbox
Folder-level permission to the Inbox, Calendar or Address Book primary folder	Open other user's folder
Delegate permission to a mailbox	Add the mailbox under "Open these additional mailboxes" under account advanced settings
Folder-level permission to the Task and Note primary folders	Add the mailbox under "Open these additional mailboxes" under account advanced settings
Top-level mailbox level permission to access the top-level folder and other custom folders	Add the mailbox under "Open these additional mailboxes" under account advanced settings
"Full Access" permission to a mailbox on Exchange	Use your own credentials to add an additional Exchange account

Opening additional mailboxes

As an alternative to these methods, you can add another Exchange account by using additional mailboxes credentials. This method is not recognized as adding a shared mailbox, because you are adding the additional account by using its own credentials. To open the additional Exchange account, follow these steps:

On the Tools menu, click Accounts.
Click the plus sign and then click New Account to add an additional Exchange account.
In the E-mail address field, enter the email address of the shared mailbox.
Under Authentication, enter the credentials for the shared mailbox.

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