Spam filter configurator Introduction With the growth of the Internet, junk mail has become a problem. Not only you want to protect your users from receiving junk mail from well known site, you also need to control who may use your mail server to relay mail. Some spammers will try to use your mail server as an exploder. You can control this. 11.. PPrriinncciippllee When your mail server receive an email message, there are two possibilities. The mail is sent to one of your domains and it is accepted, or the mail is not meant for any of your domain and the sendmail daemon will try to relay it appropriately to the proper mail server. There is a third possibility: The message is sent to one of your users, but originated from a well known junk mail sender. You may want to delete it right away. 22.. UUssiinngg nnaammee oorr IIPP nnuummbbeerrss Mails may come from machines which are identified using the host name and sometime using their IP number. It is sometime more practical to classify machine based on their IP number instead of their domain name. In the following section you will see that sometime you are allowed to enter a name, sometime an IP number, sometime both. 22..11.. SSppeecciiffyyiinngg aa nneettwwoorrkk You can specify a network number by simply entering the prefix of the IP number for that network. For example, for the class C network 192.168.1.0, you simply enter 192.168.1. 22..22.. SSppeecciiffyyiinngg aa hhoosstt oorr aa ddoommaaiinn To specify a host name, you enter the fully qualified name, like machine1.domain.com. To specify a domain, simply enter it. This means that any machine part of this domain will be processed in the same way. 33.. SSeettttiinngg rreejjeecctteedd sseennddeerrss You simply enter a list of email address, host name, domain and IP numbers. All the following possibilities are allowed: · spammer@junk.domain · junk.domain · D.X.Y.Z · C.X.Y · B.X · A You must also enter an error message which will be sent back to the sender. 44.. SSeettttiinngg ""rreellaayy ffoorr"" bbyy IIPP You enter here a list of IP number (host or networks) for which your server will relay mail. You generally enter here the various local IP networks. 55.. SSeettttiinngg ""rreellaayy ffoorr"" bbyy nnaammee You enter here a list of host name and domains for which your server will relay mail. You generally enter here the various domains in use on your local network. 66.. SSeettttiinngg rreellaayy ttoo hhoossttss You enter here a list of mail server for which your server is normally a gateway.