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anti-spam_and_anti-virus_measures [2014/05/09 11:43] (current)
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 +{{ :​webvanced_e_mail_spamfilter.jpg?​nolink|}} ====== Anti-spam and anti-virus measures ====== ​
 +
 +
 +----
 +
 +===== DNS Blacklists =====
 +When mail arrives at our mailserver, our first line of defense is sendmail'​s mechanism to consult various DNS blacklists. These are lists maintained on the internet containing the IP addresses of know spammers. This mechanism is quite successful in stopping a large percentage of all unwanted mail (see statistics),​ but it cannot recognize spam when sent from a new, unknown source, so it cannot be the only defense. ​
 +We have supplemented the DNSBL mechanism by some additional rules, like blocking mail where the sender address does not resolve to a valid internet address.
 +
 +----
 +===== MailScanner =====
 +All mail, after passing the acceptence test, is processed through MailScanner,​ which is programmed to take the following actions:
 +
 +  - Process mail through SpamAssassin for spam tagging; ​
 +  - Ordered List ItemProcess mail through the ClamAV and McAfee virusscanners; ​
 +  - Ordered List ItemQuarantine mail reported to be infected by a virus, or mail containing dangerous attachments or dangerous html. 
 +
 +Note: as of 18 November 2003, our MailScanner configuration ads a header with the short summary of the virusscan:
 +
 +**''​X-LeidenUniv-MailScanner:​ Virusscan: Found to be infected
 +''​
 +**
 +
 +for infected mails, or "Found to be clean" for uninfected mails.
 +
 +----
 +===== Quarantine =====
 +If a virus or dangerous attachment is detected, you will receive a mail where the dangerous part has been stripped out and replaced by a virus warning like this one:
 +
 +''​This is a message from the MailScanner E-Mail Virus Protection Service''​
 +
 +----
 +
 +''​The original e-mail attachment "​eicar.com"​
 +was believed to be infected by a virus and has been replaced by this warning
 +message.''​
 +
 +
 +
 +
 +
  
anti-spam_and_anti-virus_measures.txt ยท Last modified: 2014/05/09 11:43 (external edit)