Administrator's Guide - Kerio Software Archive

Chapter 16 Antispam control of the SMTP serverFigure 16.5Custom RulesRule DefinitionOn the tab, each filtering rule is represented by one line (see figure 16.5). Using matchingfields on the left you can activate or disable individual rules. This way you can switch therules temporarily on and off without the need to remove them and add them again.When creating rules, bear in mind that their order in the list is very important. Individual rulesare processed in the same order as listed, downwards. Rules in the list can be reordered bythe arrow buttons on the right. Simply select a rule in the list and click the arrows to move itup or down.Rules can also be moved by the Drag and Drop method, i.e. by dragging and moving rules bymouse.It is essential to consider twice especially location of denial and allowance rules since oncethese rules are processed, no other rules are applied. After rules where only score pointsare added or taken off, other rules are processed unless all of them are applied or unless themessage matches a permission/denial rule.Note: Rules tested against From and To headers have a peculiarity which might be beneficial.If these rules go before the others, they will be tested on level of SMTP traffic. In case ofdenial rules, messages matching such a rule are blocked even before accepted to the queueof incoming messages. This decreases the load on the server. It helps the server avoid takingseveral actions and using of several tools such as antispam tests and antivirus control whichis applied once a message is accepted to the queue of incoming messages. In case of permissionrules, no other rules are applied if they are tested on level of SMTP traffic. For detaileddescription on testing of headers, see below (the Headers section).Click the Remove and Remove unused buttons to delete rules from the list.178