Processing for Incoming Messages

If the Quarantine function is enabled, all inbound message senders are checked against the quarantine whitelist. If the sender is whitelisted, the message is processed as normal. If the sender is not on the whitelist, the message is held in the quarantine pending queue.

In addition, if the Challenge Response system is enabled, a Challenge Response email is sent to the sender, which allows them to authorize themselves by visiting a web-page and effectively confirming he/she is a real person.

Figure. Quarantine process.