DNSBL services to check for blacklisted senders, known open relays, servers in dialup IP ranges, etc.
advanced Bayesan filtering to classify messages based on their text content. The filtering engine can be easily trained by the users to improve its accuracy. Learning is as easy as clicking on 'This is spam' and 'This is not spam' links
user-defined spam probability threshold for spam classification
spam folder to quarantine messages
per-user and shared whitelists to ensure messages from particular addresses or domains are never classified as spam
all user's contacts are automatically whitelisted
daily spam report to notify every user of how many messages were classified as spam each day (can be disabled)
Anti-Virus
scanning of incoming and outgoing emails and attachments, before they reach the inbox or the webmail
quarantine of all suspected emails
scanning of all files uploaded by the users to the system
