XE-Filter Questions

Every inbound message must pass up to four filtering checks before being cleared for delivery.  These four layers of protection can remove over 95% of all spam email before it ever reaches your existing spam filter.

XE-Filter tests are ordered to provide the quickest, most efficient method to filter incoming email. 

For example, DNSBL tests are performed last since the query process is often slow and must wait for responses from remote and possibly distant servers. 

To speed up the DNSBL process, XE-Filter maintains a locally held cache of recent blacklisted IP addresses, preventing repeated queries on the same IP address.