Use CubexSoft MSG to EML Converter to successfully fulfil the batch migration of MSG to EML at once. It converts MSG to EML without Outlook email client. The size of an MSG files does not an issue in this method. The software preserves all attributes in its authentic form in the resultant outcome. This app is well matches with Mac and Windows OS. Also provides a demo option that allows free migration 25 MSG to EML.

https://www.cubexsoft.com/msg/