Roundcube is not the email server, it is just an email client like outlook.
In order to send mail using external scripts, you need:
- Username (user@example.com)
- Password
- Host / Server: box.example.com
- Port 587
- Encryption: Either STARTTLS or TLS
DO NOT use SSL for SMTP. If you are looking to do mass email, I suggest using https://www.mailgun.com/.
I don’t know python but my google search suggests https://docs.python.org/2/library/email-examples.html is the best place for an example on using the python package “smtplib”