Antispam Overview

IMail standard edition includes standard antispam technology; IMail Plus and Premium editions include Premium as well as standard antispam technology. Premium Antispam features Mail-Filters™ language-aware, hand-tuned, constantly updated antispam technology. It implements a combination of off-site identification and spam processing at the IMail Server. By sending frequent updates to the IMail Server, Mail-Filters ensures maximum catch rates and low false-positives.

IMail Standard edition includes standard antispam features. These features are custom configured by the administrator to identify spam and prevent it from clogging your Inbox. Mail messages are passed through several layers of filters and tests to assure that maximum spam detection is achieved.

What You Can Do with the Antispam Features

• Use the Premium Antispam filter (optional in the IMail Premium and Plus suites only) to automatically manage spam protection. Premium Antispam filter settings are applied before Standard Antispam filter settings.
• Enable statistical filtering (content filtering) to analyze each message and determine if it is spam.  
• Use phrase filtering (content filtering) to configure a phrase list The phrase list contains a list of spam phrases. For example, if you frequently receive spam that uses the phrase "wholesale products" then can enter it into the phrase list. Phrases are stored in the phrase-list.txt file, which is located in the mail domain's directory. that searches for specific spam phrases within the subject and body of email messages.
• Enable HTML feature filtering to search messages for HTML tags that could be used to disguise spam.
• Create a URL Domain Black List that searches for domain names (URLs) contained within HREF and IMG SRC HTML tags and in plain text messages.
• Enable broken MIME header filtering to treat emails with malformed MIME headers as spam.
• Use the Sender Policy Framework (SPF) feature to increase the ability to stop incoming email from forged email addresses (spoofed email).
• Use connection filtering to compare email messages against configurable DNS black lists to determine if they are from IP addresses that are known to send spam.
• Create a white list (trusted addresses) of email addresses, domains, and subnet masks that bypass content filtering.
• Enable verification checks (connection filtering) to verify the "Mail FROM" address, HELO/EHLO domain information, and perform a reverse DNS lookup on incoming email messages.
• Configure delivery rules to trap messages based on spam X-Headers that are inserted when a mail message fails a spam test.

Which Antispam Settings are Used to Check a Message?

The antispam filters used to scan a message are determined by the IMail domain settings of the IP address that the message is received on.  If the message is received on an IP address that is not configured for IMail, the primary domain's antispam filter settings are used.

Spam Actions

If a message is identified as spam, you can set IMail Server to delete it, send it to an email address, or insert an X-header in the message to identify which spam test it failed. You can also create delivery rules to search for the spam X-Headers and process the message accordingly.

Accessing the Antispam Features

The Antispam options are accessed from two levels: the server level and domain level.

Related Topics

Antispam Configuration Overview