theruziev/async_sender ? reverse-engineered prompt

Build me a small Python library called AsyncSender that lets me set up an SMTP connection and send email messages asynchronously in a really simple way.

I want a clean Mail class I can use from async code, plus a Message class for creating an email with a subject, sender, recipient, and body. It should feel easy to use, like I can create a mail client, send a message, and not have to deal with a lot of setup.

Please include a basic README with a quick example, and make sure the package can be installed and used like a normal Python library. If you need to check current Python or SMTP best practices, look up the latest docs online. Also add a few tests so I know the main send flow and message creation work correctly.