Users in an on-premises Exchange Server or Exchange Online environment can't use Outlook on the web (formerly known as Outlook Web App [OWA]) to open a shared document that resides on a network drive. When a user opens an email message in Outlook on the web and then clicks the link to the shared document, the document doesn't open.
This behavior is by design. In Exchange Server and in Exchange Online in Office 365, you can't use Outlook on the web to access shared files through a Universal Naming Convention (UNC) path.
Do one of the following:
- In Outlook on the web, right-click the link in the email message, and then click the option to download the file to your local computer.
- Use Outlook to view the email message, and then open the file directly through the link.