ACTIVATING THE ANTI-SPAM CAPABILITIES
The anti-spam module of Internet Exchange provides you with options to control the reception of unwanted messages. It also provides control on what sites can use Internet Exchange as a mail relay. The anti-spam configuration is presented in a two-column table format. The left column contains the Spammer Address/Domain Restriction parameters, while the right column contains the IP Address Access Control parameters.

To configure the different anti-spam capabilities do the following:
  1. Tick the check box of the Anti-Spam capabilities you wish to enable namely:


    • MAIL FROM during SMTP connection
      If enabled, SMTPD will scan for known/configured address or domains during the MAIL FROM SMTP command; and will return a 553 error to the remote host if a match is found.

    • From:
      If enabled, the anti-spam module will scan any addresses and domains in the From: header.

    • Reply-To:
      If enabled, the anti-spam module will scan addresses or domain in the Reply-to: header. The anti-spam module also allows the system administrator to specify whether to reject spam messages with a permanent or temporary SMTP Error Code. If the Permanent radio button is selected, the mail messages will be rejected by SMTPD with a Permanent SMTP error code, and will be bounced back to the original sender by the peer MTA. On the Other hand, if the Temporary radio button is selected, the messages will be rejected by SMTPD with a Temporary SMTP error code and will usually be queued up and re-tried by the peer MTA later on to the recipients. The default is set to Permanent.

    • Resent-From
      If enabled, the anti-spam module will scan addresses and domains in the Resent-from header.

    • Sender
      If enabled, the anti-spam module will scan addresses and domains in the Sender header.

    • Return-path
      If enabled, the anti-spam module will scan addresses and domains in the Return-path header.

    • Reject Domain without MX/A Records
      If enabled, SMTPD rejects the connection if there is no MX or A record defined in the DNS for the sender's domain.

    • Enable RBL Lookup
      When enabled, SMTPD will try to find and match IP addresses of remote sites against network databases of known spammers. These databases consists of lists of IP addresses that are known to send SPAM mail be friendly to spammers, and/or totally open to mail relaying. If this option is enabled, the anti-spam module will have additional spam mail detection capabilities.


    • Reject with SMTP Error Code
      The anti-spam module also allows the system administrator to specify whether to reject spam messages with a permanent or temporary SMTP Error Code. If the Permanent radio button is selected, the messages will be rejected by SMTPD with a temporary SMTP error code and will usually be queued up and re-tried by the peer MTA lated on to the recipients.


    • Enable Reverse DNS lookup
      By activating this option, reverse DNS lookup is performed during the SMTP session. During the HELO/EHLO session, the SMTPC identifies itself to the SMTP server (SMTPD) through the HELO/EHLO parameter. The SMTP server verifies if the domain name corresponds to the IP address of the SMTP client host by performing reverse DNS lookup.


    • Reject Non-Resolvable IP
      When enabled, SMTPD rejects the connection if the incoming IP address is non-resolvable which means that there is no DNS (PTR) record for this address.


    • Reject with SMTP Error Code
      The anti-spam module also allows the system administrator to specify whether to reject spam messages with a Permanent or temporary SMTP Error Code . If the Permanent radio button is selected, the messages will be rejected by the SMTPD with a Permanent SMTP error code, and will usually be bounced back to the original sender by the peer MTA. On the other hand, if the Temporary radio button is selected, the messages will be rejected by the SMTPD with a Temporary SMTP error code and will usually be queued up and retried by the peer MTA later on to the recipients.


    • Reject Non-Match Host/Domain
      When enabled, SMTPD matches the resolved domain name with the one declared by the remote SMTPC. If the two do not match, the connection is denied. It is also used to compare the reverse address look-up values but does not continue to check for possible CNAME entries.


    • Allow/Deny Incoming SMTP connection by default
      If the "Allow Incoming" option is selected, SMTPD accepts every IP address except for those mentioned in the Deny IP address list. On the other hand, if "Deny Incoming" option is selected, every IP address except for those mentioned in the Allow IP address list is rejected.


    • Allow/Deny Mail Relaying by default
      If "Allow Mail Relaying" option is selected, SMTP allows mail relaying for all IP addresses except for those mentioned in the Deny IP address list. On the other hand, if "Deny Mail Relaying" is selected, every IP address except for those mentioned in the "Allow IP address list" is prohibited for mail relaying.

  2. Click the Submit button to save the settings.