When you convert MSG emails in bulk, the main thing to protect is the email header. Sender name, receiver details, subject line, and date time all come from that header. If the MSG files are handled with the wrong method, these details may change or may not appear properly in the EML file.
For a large MSG folder, I would avoid manual saving. It is slow and not safe for checking every email. A better way is to use Softaken MSG to EML Converter, as it can process multiple MSG files and keep the original email details, including sender, date, body content, formatting and attachments. It also works without Outlook, which helps when MSG files are stored separately.
Before running the full folder, test the free demo with 10 MSG emails and open the EML files in your email client to confirm the sender and date fields.