I volunteered to maintain several mailing lists for several community organizations. They are small mailing lists with members not more than 200 each, but on hot topics, it can generate a lot of emails sent to the email server.
The mailing list uses Mailman. It sends the message to the email server on the same computer. The email server uses Sendmail, which is set up to send the messages to smart host, which is my ISP email server. The computer itself is using Fedora.