address (reverse path) is listed in the dnsbl_exempt.cfg (without the <>), any
positive DNSBL result on the sender's IP address will be ignored.
* Automatically adds ("white-lists") recipients of mail that was successfully
delivered by the sendmail thread to the dnsbl_exempt.cfg file if they're not
already listed.
* Local submit performance improvements: don't perform ip.can, host.can or
spamblock.cfg searches or DNSBL server queries for local connections (from
localhost or the same IP as the server is listening).