Mailing list subscription [closed]

I have this section on my site the call to action is :

"Subscribe to my mailing list to be notified of when my full website releases."

How do I collect email addresses and save them to a file (I'm guessing it will require some kind of php or other server side language)

HTML code is below

<div class="right">
                <p class='attention'>Website to be released <br>early-mid 2020!</p>
                <form action="mailto" method="post" enctype="text/plain">
                <input type="text" name='email' id='email' placeholder="your email">
                <button type="submit">Notify Me</button>
            </form>
            </div>