In the unlikely event that a genuine email is blocked in the spam filter, you can access a control panel to whitelist known addresses, when you email a client their email address is automatically added to the whitelist which further reduces the likelihood of a genuine email going into the quarantine. You can even click the whitelist action directly from the quarantine email which will be received daily (should there be anything in the quarantine). The quarantine email shows all email from that day that has entered the quarantine.