View Delegated or Shared Mailbox
Delegated Mailbox can be used in similar fashion, but it does belong to a specific user, and they have more control over their own email account.
AccessOptions to access another mailbox
*All these
require Outlookoptions Classicdo DesktopWithadmin regularor Desktopthe Outlookowner installed,of whenthe mailbox assigning you are delegated access to inbox, it may take an hour or so after its applied, it should automatically appear on the sidebar as another set of email folders. Sometimes you may need to fully close out of outlook and reopen it, and generally you do need to click the > icon to drop down the folders.
Online Outlook
https://outlook.office.com/mail/ Outlook
Quickest and easiest method would be to login to your email using link above, clicking on your initials in top right corner and clicking to "Open another mailbox"
Then type in and choose the email address and press open
More permanent option - (New DesktopOutlook App)and Outlook Web)
After your admin has added you as a member of a shared mailbox, close and then restart newreopen Outlook. The shared mailbox should automatically display in your Folder pane.
What if it didn't work?
Add the shared box manually.
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Select Mail from the navigation pane in new Outlook.
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In the Folder pane, right-click your account name, and select Add shared folder or mailbox.

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In the Add shared folder or mailbox window, type the name of the mailbox you want to access, for example, info@contoso.com.
Outlook Classic Desktop
With regular Desktop Outlook installed, when you are delegated access to inbox, it may take an hour or so after its applied, it should automatically appear on the sidebar as another set of email folders. Sometimes you may need to fully close out of outlook and reopen it, and generally you do need to click the > icon to drop down the folders.
For More Information: Open and use a shared mailbox in Outlook - Microsoft Support




