Filter Settings

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The following settings are available. In SpamFilter Enterprise, each email domain can be configured independently with different settings. The "ALL DOMAINS" is a reserved entry that contains default filtering values to all domains. Each domain can be given customized filter settings by clearing the "Use Defaults" checkbox.

Figure 2

Figure 2


 
Min MAPS matches needed to reject msgs - Sometimes MAPS blacklists can be too strict and list legitimate domains in their blacklists. You can reduce the number of false positive by requiring that more than one single blacklist match is found before rejecting a connection.
Max number of spaces in subject line - Many spam messages contain a large number of spaces and tabs, and SpamFilter can reject emails based on this setting. Enter a “0” to disable this filter.
Image filter threshold SpamFilter scans inside images embedded in emails to detect spam signatures. Use this setting to adjusts the threshold of the image filter. The higher the threshold, the more aggressive the filter. Enter a “0” to disable the image filter.
0-Day filter - Many spammers register bogus domains for the sole purpose of sending spam, and use them right away. Legitimate domains usually take longer to purchase, configure, test and implement the new domain name. SpamFilter can reject emails if the domain is recently registered (by default less than 30 days before the email is received).
Reject if no reverse DNS - SpamFilter can be configured to reject emails if the remote server does not have a valid reverse DNS PTR entry.
Reject if sender domain has invalid MX record SpamFilter can check to see if the senders email domain has a valid MX record. If the MX record is not present in the DNS, the email will be rejected. The email domain in this case is what follows the “@” sign in the senders email address. For example, is the sender is user@sub.domain.com, the domain that will be tested for the presence of an MX record is sub.domain.com.
Reject if Empty "Mail From" - If this option is checked SpamFilter will reject all emails with an empty "Mail From" field. Please note that this setting will delete legitimate email, as in email receipt notifications and some error emails.
Reject if "Mail From" = "Mail To" - Reject all emails where the sender's email is the same as the recipient's email. Note that this causes problems with users who send emails to themselves using EBay's web interface for example.
Reject if "From Domain" = "To Domain" - SpamFilter can reject all email where the sender's domain is the same as the recipient's domain. Usually your users will not go thru SpamFilter when sending emails to themselves, Spammers often use this technique
Resolve URLs in emails & check IP in MAPS - SpamFilter can optionally resolve all URLs embedded in an email message to IP addresses, and then check those IP addresses in the MAPS servers to see if any of them are being blacklisted.
Allow % in address - SpamFilter can then optionally check to see if the recipient address has a % sign in it. Many SMTP servers are susceptible to being tricked into relaying mail with this. Ex. if you are isp.com, then a spammer could try to use joe%yahoo.com@isp.com to relay mail to joe@yahoo.com if your server is vulnerable.
Include email in "From:" header when verifying MAIL FROM sender - Use this option to include the email address in the "From:" header, in addition to the real envelope email address specified in the MAIL FROM command, when checking the sender's email agains the "FROM Emails" blacklist, the "Domains" blacklist, the "Excluded FROM Emails" whitelist, and the "Excluded Domains / IPs" whitelist.
Tag Spam & Deliver - Allows to tag spam by adding the header "X-SF-SPAM:Y" to email classified as spam. The email is then forwarded to the destination SMTP server. This allows administrators to handle spam as they wish on the back-end.
Tag Spam in Subject & Deliver - Allows to tag spam by prefixing the word SPAM: in the subject line of emails classified as spam. The email is then forwarded to the destination SMTP server. This allows administrators to handle spam as they wish on the back-end.
Tag Whitelisted emails in Subject - When checked, this option causes SpamFilter to add a tag in the subject line (customizable via the "WhitelistTagPrefix" parameter in the SpamFilter.ini file) to indicate that the email was whitelisted.