Administrator's Guide - Kerio Software Archive

Chapter 16 Antispam control of the SMTP server3. In the If the message has invalid Caller ID, then section, set spam rating to 3 points (asexplained above, spam messages are tested and scored by multiple tests so it is not recommendedto block it or to set individual scores too high).4. It is also recommended to enable the Apply this policy also to the testing Caller ID recordsoption since most servers which employ the Caller ID technology use its testing mode sofar.5. If you use an alternative (backup) SMTP server, specify its address in the Don’t check CallerID from IP address group entry.SPFFor closer description of the SPF technology, refer chapter 16.5. Recommended settings of theSPF test is almost identical with the Caller ID settings. It is as follows:1. Open the SPF tab under Configuration → Content Filtering → Spam Filter).2. Enable the SPF check of every incoming message option.3. In the If the message has invalid Caller ID, then section, set spam rating to 3 points (asexplained above, spam messages are tested and scored by multiple tests so it is not recommendedto block it or to set individual scores too high).4. If you use a backup SMTP server, enter its address in Don’t check SPF from IP addressgroup.It is also recommended to support SPF by adding a record regarding SMTP servers which areallowed to send email from your domains to your DNS records.Spam repellentDetailed information on Kerio MailServer’s Spam repellent technology, refer to chapter 16.6.This technology is not involved in spam rating and it is therefore only mentioned in thissection. The technology usually sorts out large volume of spam even before it is accepted inKerio MailServer and thus decrease the load on the antispam tests and on the mailserver inparticular.The optimal settings of Spam repellent are as follows:1. Open the Spam Repellent tab under Configuration → Content Filtering → Spam Filter).2. Enable the Delay SMTP greeting by ... seconds option and set the value to 25 seconds.192