Unfortunately, Mailman has no way to control the rate at which messages are sent. It is therefore not supported on our shared or reseller web hosting servers.
Our Email Policy states that shared and reseller web hosting users can send a maximum of 500 emails per hour. Equivalent to sending 1 email every every 8 seconds. Mailman has no way of restricting (throttling) itself to these limits. Using Mailman even send a small mailing list, would most likely lead to your account being suspended.
We recommend using PHPlist as an alternative to Mailman. PHPlist supports throttling and can be easily installed through your hosting control panel.