

When the Enter password dialog opens, click the Sign in with another account link.Enter the shared mailbox email address in the address field.Outlook will close click on your Outlook shortcut to reopen it.In File, Account settings, choose Change Profile.Use these steps with the new, " simplified account dialog". If the mailbox is added using the Open Additional mailbox command in Account Settings, remove the mailbox from your profile in File, Account Settings, More Settings, Advanced. To avoid these problems, create a new profile for the shared mailbox instead.

There can be issues if you have delegate permissions on the shared mailbox or it’s automapped (eg, is added to your profile automatically), so you or your admin will need remove delegate permissions or disable automapping before you add it to your profile. The only way to get around this is to add the shared mailbox to your profile as a mailbox.
