EML files are often required to perform drop test on DLP network Monitor, methods used previously to generate such files are complicated because the compatible applications (like Windows Live email & Outlook Express) are not available anymore on windows 10.
The EML files can also be generated using GMAIL using steps below.
Component : DLP Network Monitor
In Gmail create the test email with desired content in the body or in the attachment, save this email in your Inbox/sent items or in Drafts.

Fig. 3. Choosing a file format for an email exported from Gmail.