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Shared mailboxes not showing all emails:
This is caused by a default setting that caches shared folders. To resolve this and see all emails in a shared mailbox, disable the caching of all shared folders in Outlook 2010 and later versions. To complete that, please follow these steps:
- On the File tab, click Account Settings in the Account Settings list.
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- In the Account Settings dialog box, in the Email tab double-click your Microsoft Exchange Server account.
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- In the Change Account dialog box, click More Settings.
- In the Microsoft Exchange dialog box, click the Advanced tab.
- Uncheck the "Download shared folders" check box
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- Click OK two times.
- Click Next, click Finish, and then click Close.
- Restart Outlook.