We want to restrict the user from sending message to his/her mail server if the message quota has been reached. This way we can limit the dead mail on the server due to undeliverable message coming from the user itself.
Subject: There are commercial tools
Sherpa makes Mail Attender which stops a user from sending an email if their mailfile is over quota (you have to use their Quota application in addition).
Otherwise, you could write code that for an OnSend event would look at the user’s mailfile size and their quota and then stop them if they are over quota. You’d need to have this code in the memo, reply and reply with history forms.