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:
-
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.
- Click the Submit button to save the settings.