Administrator's Guide - Kerio Software Archive

16.2 Blacklists tabtration Console — for details, see chapter 13.2).The **SPAM** string is used as a default text. The string can be modified in the Mark themessage as spam section (for details, see below).TIP: If you use the [%s] referent for the Prepend message’s Subject with text entry specification,the score evaluation (represented by asterisks) assigned by the antispam protectionsystem is inserted into this textfield. This implies that users can define one of morecustom antispam rules (depending on the number of asterisks) in their mail server or inthe Kerio WebMail interface.Send bounce message to the senderThe server returns the sender a DNS message informing that the email message cannotbe delivered.It is not recommended to use this option since most of spam message use false senderaddresses. This implies that the denial message cannot be delivered (the address to whichthe DNS message is sent might not exist). Messages with the information about theirrejection are then kept in the queue where they must be removed manually. Otherwise,the server attempts to deliver them in intervals set in the queue settings (every 30 minutesfor five days, by default). Undeliverable messages are discarded.Forward the message to quarantine addressEnter an address to which blocked messages will be forwarded (regardless of other settingsof the antispam filter). Headers of such messages include information on tests havingbeen applied to the message along with score set by individual tests. If a legitimatemessage blocked by the tests is included in the box, it is possible to use the informationto optimize the tests.For this purposes, it is recommended to create a special email account (e.g.spam@company.com) where copies of spam messages will be delivered and stored.16.2 Blacklists tabKerio MailServer can also block incoming messages from servers that are considered as spamservers. For this purpose, it uses public databases of these servers located in the Internet orits proprietary database.To define these parameters go to the Blacklists tab in Configuration → Spam filter section.List of trustworthy IP addresses (whitelist)So called blacklists, i.e. spammer databases, can occasionally include servers which sendlegitimate mail. This may occur for example when an SMTP server is not secure enoughand it is misused for spam sending. Therefore, Kerio MailServer includes a list of trustworthyIP addresses (so called whitelist). In this list, IP addresses considered by themailserver as spammers can be added. In future, these addresses will be considered astrustworthy, even though they may be included in a blacklist used by Kerio MailServer.Messages from the servers included in the whitelist are not tested against blacklists andthey are let in automatically. Other types of antispam tests, however, will not apply tothem.173