Browsers are client-side applications software and client-side application cannot send an email. You need a client-side application software which should connect with some server application. Some softwares(ie outlook, thunderbird) are configure with mail server using SMTP, POP3 and IMAP protocols. Script code can open outlook or thunderbird from your web browser.
You can invoke mail application by using HTML or JavaScript. Left side of the tool page has setting options, change setting and generate instant code.