Files with the EML extension are e-mail files. Microsoft released a hotfix for Outlook 2007 to fix an issue with opening these files. If you are unable to open a file with the EML file extension in Outlook 2007, but can open the file in Outlook Express, Windows Mail or Internet Explorer, you need to download the fix and update your installation of Outlook.
Verify that you can open the file with the EML extension in another program, such as Windows Mail. Open Windows Mail, and then use "File," and "Open" to open the file.
Download the fix from Microsoft (full link in Resources). Apply Hotfix 957909, dated September 24, 2008. Alternately, follow the link in References, and then press the "Fix It" button to automatically update your software.
If Outlook 2007 still does not allow you to open the file, download an EML Viewer program, such as EML Viewer Pro, which offers a 14-day free trial, Email Open View or EML Viewer, which are both free (full links in Resources).
Open the file in the selected program to bypass Microsoft's security measures and view the file contents.
Confirm that you know from whom you received the email with the file with the EML file extension. These files are associated with viruses that can harm your computer.