Apache SpamAssassin vs MX Guarddog

Apache SpamAssassin is free, open-source software that classifies email to help system administrators block unsolicited bulk messages. It runs on a server to filter mail before it reaches a mailbox. Detection combines header and text analysis, Bayesian filtering, DNS blocklists, collaborative filtering databases, and local and network tests. Its scoring framework and plugins add heuristic and statistical checks. Tests and configuration are stored as plain text, so administrators can adjust settings and add rules. The Mail::SpamAssassin API can be integrated with systems such as procmail, sendmail, Postfix, and qmail. The core distribution includes command-line filtering tools and Perl modules for use in other products. The downloads page lists version 4.0.2 as the released version. Official releases are signed, with GPG signatures and SHA-256 and SHA-512 checksum links for downloads. Users can ask questions on the mailing list; developers and PMC members answer as time permits.

MX Guarddog is a hosted email gateway for standard SMTP servers serving owned domains. It scans incoming messages for spam, phishing, malware and viruses, quarantines offending mail, and forwards clean messages to the customer’s server. The service runs in the cloud, so it requires no hardware or software installation and no configuration changes to email clients or the server. Quarantine reports summarize stopped spam, and users can adjust report preferences; quarantine retention is seven days. If a customer’s server is unavailable, MX Guarddog says it holds mail for up to 168 hours and delivers it when the server returns. It can sync active addresses from Windows AD, LDAP or cPanel, and says it uses Transport Layer Security, including Perfect Forward Security, for email in transit. The listed per-address price is $0.25 per month; aliases are not charged. A free plan and 30-day trial are listed. The service is for web use and does not support consumer Gmail or Hotmail accounts.