If you've decided to run MSG Viewer for Outlook to convert a batch of MSG files, you may wish to import the converted EML files back into your mail client for ease. Please consult your email client's documentation for help. For instance, in Apple Mail, you can use the "File → Import Mailboxes.." command, selecting the "Apple Mail" option as your source for importing data.
One tip! If you would like to batch import an entire folder full of EML files, Apple Mail will create individual folders for each EML file after import, which is often undesirable. To get around this issue, just rename your folder to have the '.mbox' extension. For example, "Team Reports.mbox" instead of "Team Reports". Now, follow the above instructions, and it will file the messages into a single "Team Reports" folder.
If you'd like to use Gmail, Hotmail, or another Web-based email client please see this FAQ.