Loop Detection

ListManager automatically tracks how many messages per day are sent from a foreign address to a ListManager address. If the number of messages in one day exceeds the Loop Detection threshold, ListManager cuts off the mailings, issuing a single refusal message, and then discarding the rest of the messages in that 24 hour period.

This feature is useful for automatically breaking mail loops that aren't able to be stopped through ListManager's other mechanism, and also for stopping a mail bomb attack. Say, for example, that someone sets their email program to send thousands of messages to your auto-responder, in order to mail bomb you, and tie up your server, this feature will detect this, notify the administrator and automatically stop the process.

Note: Some sites use a Web CGI script to sign people up to their list. In such a case, the script might be sending from the same address every time, and to the same address every time, thus being perceived as a mail loop if the quantity of mailings goes over the loop detection threshold. In such a case, you should put an exception for that specific from/to combination to exempt your script from this logic. If you forget to do this, the server admin will receive notification of the potential loop, and you'll thus be reminded of the need for an exception.