UserGate Mail Server

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Content Filtering

 
UserGate Mail Server will start content filtering after the message body has been received. The first step is to check MIME headers. If the message delivery route specified in the header is longer than the set limit (“Maximum redirect depth” parameter on “Communication Server – Settings” page), UserGate Mail Server will block the message. Besides, a reply message will be generated at the MIME check step if the Autoreply function is enabled.
 
The next step is to check the entire message using an online service (the so-called Cloud Antispam). The application sends a unique message hash to a remote server using the HTTP POST method. Cloud Antispam requires HTTP to be enabled on the computer where UserGate Mail Server is installed. Messages identified as spam or infected messages (Cloud Antispam also scans messages for viruses) are placed into the quarantine folder (%CSE%\mail\quarantine). You can push messages in the quarantine folder to their destination addresses. To do so, move the corresponding *.xeml file of a message from “%CSE%\mail\quarantine” folder to “%CSE%\mail\import” folder. To push-send a message, use the shortcut menu on the “Monitoring” page.
 
NOTE! Quarantine folder is periodically cleaned. Cleanup settings are configured in the Anti-Spam – General Settings section of the Administrator’s console. You can schedule folder cleanup specifying the cleanup period in crontab format (see http://en.wikipedia.org/wiki/Cron). The default cleanup period is 30 days.
 
Next, UserGate Mail Server completes SURBL filtering and statistical check (Bayesian filtering). The Bayesian filtering algorithm designed by Entensys allows automatic learning using the messages identified by Cloud Antispam as “clean messages.” The last step includes virus check and message processing using the rules.