MSG to EML conversion is useful when Outlook MSG files need to be opened in Thunderbird, Windows Live Mail or other EML supported apps. Manual saving may work for a few emails but it becomes slow when there are many MSG files.
If formatting is important, first test a few emails that contain tables, links or HTML text. This helps confirm that the message body, subject, sender details, date and attachments are coming correctly in the EML output.
For this case, WholeClear MSG to EML Converter can be used as a practical option. It supports bulk MSG to EML conversion, so each message does not need to be handled one by one.
My suggestion is to keep a backup of the original MSG folder before starting. After conversion, open a few EML files in the target email client and compare them with the original MSG files.