There are many ways to be able to convert EML files to MSG format, such as using an email client or specialized conversion software. These are the instructions for the two most commonly used methods.

Option 1: Through an email client (e.g. Microsoft Outlook):
- Launch Microsoft Outlook on your desktop.
- Create a new folder in Outlook to store MSG files.
- Move EML files to this folder by dragging and dropping them.
- Outlook will automatically convert EML files in this folder to MSG format.

Source: https://www.trustvare.com/eml/

Option 2: Via third-party conversion software (such as TrustVare EML converter):
- Choose a reliable conversion software like "TrustVare EML Converter".
- Download and install the EML Converter software on your device.
- Launch the software and upload the EML file you want to edit.
- Fix the approach to save the results in MSG format.
- Start the conversion process and the software will start converting the EML file to MSG.
- Save the MSG file to the chosen location after the conversion is complete.

It can be useful to use conversion software to process numerous files at the same time or to manage a large number of files. It is recommended that you save the original files before starting any changes. Also, make sure that the method or software you choose is compatible with your system and the specific types of files you want to convert.