In most cases, if other applications open when clicking a MSG file, this is because MSG Viewer for Outlook is not configured to be the default application when opening MSG files.

You can get around this issue by right-clicking on an MSG file and choosing "Open With → MSG Viewer for Outlook".

However, to set MSG Viewer for Outlook to the default application:
  • OS X 10.6-10.7 (legacy version): Double-clicking the MSG Viewer for Outlook application
  • OS X 10.8+: In Preferences, click 'Associate MSG files' button at the bottom (non-AppStore only).
  • We've made a separate download that will perform this association (no need to install, just double-click the 'SetDefaults' app). This is mainly for our AppStore customers who do not have this feature due to sandboxing restrictions, but can be used by anyone.
  • Alternatively, please visit this link to learn how to change the default file associations on your Mac.
  • In some cases, Parallels Desktop may also be overriding the file association to open the MSG file in Windows, see this link for additional help on changing those settings.

If the problem only happens when clicking an EML file, this is because your default Mail client on your Mac is set up differently than you would like. Please visit this link.

Pro tip: If these tips don't work, you may need to reboot your computer or empty the Trash to delete any older copies of Outlook MSG Viewer or MSG Viewer for Outlook that may be interfering. Please also confirm that your default email client is set up correctly in the "Customizing MSG Viewer for Outlook" section above. It is possible that the MSG file is converting properly, but a working email or address book client has not been properly configured.