Anti spam

General

Spam mark threshold

When hMailServer runs spam protection, each spam protection mechanism gives a score. If the total score of the message exceeds this value - but stays below Spam delete threshold, the message will be marked as spam.

  • Add X-hMailServer-Spam - Adds a X-hMailServer-Spam MIME header to the email message.
  • Add X-hMailServer-Reason - When enabled, hMailServer will add a message header which contains information on why hMailServer considered the email to be spam.
  • Add to message subject - Using this setting, you can specify a text that hMailServer should prepend to the message subject. In combination with rules, spam messages can be moved to specific IMAP folders.

Spam delete threshold

When hMailServer runs spam protection, each spam protection mechanism gives a score. If the total score of the message exceeds this value the message will be deleted and not delivered to its recipients.

Maximum message size to scan (KB)

If the size of an email message exceeds this size, hMailServer will not scan it for spam. In most cases, spammers sends small messages to save bandwidth so scanning large messages serves no purpose in most cases. Scanning large  messages for spam may require a lot of CPU processing.

Spam tests

Use SPF

Select to enable spam protection using SPF.

Check host in the HELO command

Turn on this option if you want hMailServer to check the host name that clients has specified in the HELO command. According to the SMTP specification, the host given in the HELO command should match the IP of the client. Enabling this may stop spam, but is also a violation of the SMTP RFC - if you have configured your server to delete spam messages. If you have configured your server to deliver spam messages but modifying the Subject header, it is not a violation of the SMTP RFC. Technically, hMailServer checks the A record for the given host to see if it matches the IP address of the connecting client.

Check that sender has DNS-MX records

If you enable this option, hMailServer will check that the senders domain has valid MX records in the DNS. If not, hMailServer will treat the message as spam.

Verify DKIM-Signature header

If you enable this option, hMailServer will look for a DKIM-Signature header in every incoming message. If a header is found, hMailServer will verify that the message content matches the signature. If it does not, the message is classified as spam.

SpamAssassin

Use these options if you want hMailServer to integrate with an existing SpamAssassin installation.

Host name

This is the host name of the SpamAssassin server hMailServer should connect to. If SpamAssasin is running on the same computer as hMailServer, the value should be "localhost" (without quotes).

TCP/IP port

Specify the TCP/IP port the SpamAssassin server is listening to. By default, SpamAssassin listens on port 783.

Use score from SpamAssassin

If this option is selected, hMailServer will use the spam score given by SpamAssassin and add it to the hMailServer spam score. If the option is de-selected, hMailServer will use the score specified in the Score text box.

Advanced

Tarpitting

Tarpitting is an antispam technique that works by slowing down the communication with spammers.

Other methods

Related

User guide

More detalied descriptions on how the different anti virus options work can be found in the user guide user guide.

 

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