Marvin: The Mail Gauntlet
The Mail Gauntlet
Sendmail
Sendmail set to queue-only mode, drops messages into it's queue
Sendmail chosen because of familiarity, popularity
Stock sendmail, except 1 custom ruleset
Marvin Processes
inbound - interfaces with Sendmail, handles locking and starts logging
split - creates new message with unique message ID for each recipient
virus - scans messages for viruses, currently uses McAfee
whitelist - messages matching a whitelist rule are immediately delivered
blacklist - messages matching a blacklist rule are immediately stopped
DCC - Distributed Checksum Clearinghouse. Takes hash of message and returns count
Spam Assassin - Score-based filter. Series of rules applied to messages
Razor - Takes hash of message and returns spam or not spam. Similar to DCC, user has the choice
DNSBL - Choice of 70 DNS-based blacklists
Delay - Messages can be held for a few minutes to increase the chances of a DNSBL hit
DNSBL2 - Same checks repeated after the delay