If there is not any document in the deletion while in the audit logs, it is possible that an automatic rule was setup to delete the e-mails. It is possible to check this by going to the Exchange admin Middle and looking for the mailbox policies for the shared mailbox. https://danteihdxs.snack-blog.com/36835387/how-check-advance-loans-can-save-you-time-stress-and-money