maia spam

Content Overview Integrating Amavisd-New with Postfix Installing Amavisd-New Configuring Amavisd-New Quarantine Handling Globally Sender whitelists and blacklists Per-Recipient Sender Whitelists and Blacklists (Maia Mailguard) Maia Installing and Configuration Configure Postfix for Amavisd-New ClamAV Virus Scanning Sender Policy Framework SPF Overview Postfix is a mail transport agent written by security researcher Wietse Venema. Not surprisingly, Postfix is designed from the ground up to be a highly secure system. It consists of several components, each of which runs with least privilege and none of which trust data from the other without validating it themselves. Despite the extensive security emphasis in the system's architecture, Postfix is capable of very good performance in normal conditions; because of architectural decisions, it is also fault tolerant and capable of good performance under adverse conditions such as resource starvation. Postfix supports three content inspection methods, ranging from light-weight one-line-at-a-time scanning before mail is queued, to heavy duty machinery that does sophisticated content analysis after mail is queued. Each approach serves a different purpose. The method shown in this article inspects mail AFTER it is stored in the queue, and uses standard protocols such as SMTP. After-queue inspection allows you to use content filters of arbitrary complexity without causing timeouts while receiving mail, and without running out of memory resources under a peak load. The SpamAssassin system is software for analyzing email messages, determining how likely they are to be spam, and reporting its conclusions. It is a rule-based system that compares different parts of email messages with a large set of rules. Each rule adds or removes points from a message's spam score. A message with a high enough score is reported to be spam. Amavisd-New is a high-performance and reliable interface between mailer (MTA) and one or more content checkers: virus scanners, and SpamAssassin. It is written in Perl, assuring high reliability, portability and maintainability. It talks to MTA via (E)SMTP or LMTP, or by using helper programs. No timing gaps exist in the design, which could cause a mail loss. It is normally positioned at or near a central mailer, not necessarily where user's mailboxes and final delivery takes place. When calling of Mail::SpamAssassin (SA) is enabled, it calls SA only once per message (regardless of the number of recipients), and tries very hard to correctly honour per-recipient preferences, such as pass/reject, and inserting spam-related mail header fields.

Integrating Amavisd-New with Postfix This article does not explain how to install and setup Postfix / SpamAssassin, this is explained here: Postfix -- the Sendmail Replacement Fighting Spam with SpamAssassin and Postfix If you want to set up a spam-checking gateway for all recipients, local or not, you need a way to perform spam-checking as mail is received, before final delivery. Postfix provides a general-purpose filtering directive called content_filter. The content_filter directive specifies a mail transport that Postfix will invoke after receiving a message. The mail transport hands the message to a filtering program. The filter checks the message and then either refuses it (which will cause Postfix to generate a bounce message), discards it, or reinjects the modified message into Postfix for further delivery. Messages that pass the filter are reinjected so that Postfix can operate on them almost as if they were new messages; this allows Postfix to behave properly if the content filter rewrites message headers.

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