We have focused our development efforts on creating a brilliant conversion engine between MSG (Microsoft Outlook format) and EML (universal email format). To display the converted email, we've relied on the fantastic email clients already available. That's why MSG Viewer for Outlook reads in the Outlook MSG file, and then creates a converted copy in EML format that is capable of being read by any email client!
Once a successful conversion takes place, MSG Viewer for Outlook needs a working mail client on your Mac in order to open the converted EML file (after all, you're viewing an email!), or if you prefer, you can also use the built-in Quick Look viewer or PDF export feature. If you use the EML format, it will behave as a native email on your computer -- you'll be able to reply or forward it just like any other email.
By default, the built-in Apple Mail program is used although this can be changed in your Preferences. If you haven't used this software previously, you may be prompted to set it up. We've created an easy-to-use tool for this purpose that you can use to expedite this process. You can customize your MSG Viewer for Outlook preferences to set up your preferred mail client.
You can also try right-clicking on the converted EML file and selecting a different Mail client by using Open With →. Or, try right-clicking on the file and choosing Quick Look, which will display the EML file natively.