How to recover HTML from an email with Linux?

I'm using a Linux (Debian) machine and have installed fetchmail and procmail. At the moment, he is able to retrieve emails sent to my gmail address every minute. However, the file fetchmail retrieves is not a classic HTML file, but contains characters in printable quotes.

My goal is to be able to get the HTML source code from e-mail, as I would if I opened Outlook on Windows, right-click on the e-mail and choose "Show E-mail". source code".

It is also important to be able to do it programmatically because I want to automate the task.