Frequentlyaskedquestions Spamassassin Apache Software

Apache SpamAssassin is an open-source spam filter. It uses a variety of tests to assign a “spam score” to emails. These tests include Bayesian filtering, DNS blacklists, text analysis, and heuristics. - Emails scoring above a threshold are tagged as spam. - Can change subject lines (e.g., prefix [SPAM] ). - Can quarantine or reject spam messages. - Works very well in combination with Exim and ClamAV. Key Features - Rule-Based Analysis - Uses hundreds of rules to analyze an email’s headers and content.

Scoring System - Each rule adds or subtracts points from a spam score. - Emails above a threshold (default = 5.0) are classified as spam. - Flexible thresholds allow fine-tuning for your environment. - Bayesian Filtering - Learns from previous emails (ham vs. spam). - Over time, the software improves accuracy by adapting to your mail flow. - DNS & Network Checks - Integrates with real-time blackhole lists (RBLs) to check if a sending IP is a known spam source. - Can query DNS-based reputation services (e.g., Spamhaus).

Extensible via Plugins - Supports additional plugins for: - SPF, DKIM, and DMARC validation - Language detection - Custom rules for local policies - Supports additional plugins for: - Header & Body Analysis - Examines email headers for forged sender information. - Scans the body for suspicious keywords, patterns, or obfuscation. - Detects HTML tricks used by spammers (e.g., invisible text). - Flexible Spam Handling - Options include: - Tagging emails (adds [SPAM] to subject line). - Adding headers (like X-Spam-Flag: YES ).

Quarantining spam into a special folder. - Rejecting spam outright at SMTP time. - Tagging emails (adds - Options include: - Performance Optimizations - Uses spamc (client) +spamd (daemon) for fast scanning. - Can run in parallel with ClamAV and Exim without heavy overhead. - Uses - Open Source & Community Maintained - Actively updated with new rule sets. - Free and widely used by ISPs, enterprises, and mail servers.

By using the guide below, we can easily install and setup SpamAssassin with integration into Exim on our development server. Update your package lists sudo apt update Upgrade your system sudo apt upgrade Install SpamAssassin sudo apt install spamassassin spamc spamassassin → core enginespamc → lightweight client used by Exim to pass messages to SpamAssassin Update the SpamAssassin rules SpamAssassin uses a frequently updated rule set. sudo sa-update -v Integrate SpamAssassin with Exim Edit the Exim configuration file depending on whether you use split configuration or not.

sudo nano /etc/exim4/exim4.conf.template sudo nano /etc/exim4/conf.d/main/02_exim4-config_options Uncomment the line below spamd_address = 127.0.0.1 783 Edit the Exim configuration file depending on whether you use split configuration or not. This step is necessary if you’d like Exim to return an error message. sudo nano /etc/exim4/exim4.conf.template sudo nano /etc/exim4/conf.d/acl/40_exim4-config_check_data Edit the configuration file as per below. # Add headers to a message if it is judged to be spam. Before enabling this, # you must install SpamAssassin. You also need to set the spamd_address # option in the main configuration.

# # exim4-daemon-heavy must be used for this section to work. # # Please note that this is only suiteable as an example. See # /usr/share/doc/exim4-base/README.Debian.gz # # See the exim docs and the exim wiki for more suitable examples.

# warn remove_header = X-Spam_score: X-Spam_score_int : X-Spam_bar : \ X-Spam_report warn condition = ${if <{$message_size}{120k}{1}{0}} # ":true" to add headers/acl variables even if not spam spam = nobody:true add_header = X-Spam_score: $spam_score add_header = X-Spam_bar: $spam_bar # Do not enable this unless you have shorted SpamAssassin's report #add_header = X-Spam_report: $spam_report # Reject spam messages (score >15.0) # This breaks mailing list and forward messages.

# deny # condition = ${if <{$message_size}{120k}{1}{0}} # condition = ${if >{$spam_score_int}{150}{true}{false}} # message = Classified as spam (score $spam_score) Reconfigure Exim (if needed) sudo dpkg-reconfigure exim4-config Keep your existing settings. Exim will now know about SpamAssassin. Update and Restart Exim sudo update-exim4.conf sudo systemctl restart exim4 Verify Integration Check logs while sending a test email. sudo tail -f /var/log/exim4/mainlog sudo tail -f /var/log/exim4/rejectlog For example: echo "Buy now!!!

$$$ WINNER $$$\n\nThis is spam spam spam spam." | mail -s "Buy now!!!" your-email@example.com SpamAssassin should score the message and mark it with headers like: X-Spam-Flag: YES X-Spam-Score: 7.2 X-Spam-Status: Yes, score=7.2 ... You must be logged in to post a comment.

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