In HTML you can specify a mailto: address in the <form> element’s [action] attribute.
<form action="mailto:youraddr@domain.tld" method="GET">
<input name="subject" type="text" />
<textarea name="body"></textarea>
<input type="submit" value="Send" />
</form>
What this will do is allow the user’s email client to create an email prepopulated with the fields in the <form>.
What this will not do is send an email.