haraka/Haraka

Features

• SMTP Server Implementations - Ships a full SMTP server implementation that accepts, filters, and delivers email with plugin extensibility.
• Outbound Delivery Queues - Manages outbound message delivery through an asynchronous queue for non-blocking relay processing.
• Connection Rate Limiting - Restricts the number of concurrent connections, messages per session, or rate from a single source.
• Plugin Hooks - Extends SMTP server behavior by attaching custom JavaScript functions to message processing hooks.
• High-Volume SMTP Infrastructure - Handles large volumes of SMTP traffic with high performance using a Node.js runtime and asynchronous queue management.
• Incoming Email Processors - Accepts email via SMTP and routes it through a chain of plugins for filtering and delivery.
• Asynchronous Delivery Queues - Holds relayed messages in a built-in queue and delivers them to remote servers asynchronously.
• Relay Authorization Controls - Controls which hosts or authenticated users are allowed to relay mail through the server.
• SMTP Relay Queues - Provides a built-in queue for relaying outbound messages to remote mail servers via SMTP or LMTP.
• Hook-Based Extenders - Extends SMTP server behavior by attaching custom JavaScript functions to message processing hooks.
• Mail Transfer Agents - Optimized for high-throughput email processing using Node.js event-driven architecture.
• Email Signing - Signs outgoing messages and verifies incoming signatures using DKIM to assert domain identity.
• Policy Enforcement Gateways - Filters spam, scans malware, and enforces authentication policies like DKIM and DMARC.
• Email Sender Authentication - Verifies sender identity and email authenticity through SPF, DKIM, DMARC, and reputation scoring systems.
• SMTP AUTH Integrations - Verifies client identity via SMTP AUTH and signs outgoing mail with DKIM to improve deliverability.
• Email Spam Filtering - Passes messages through SpamAssassin or rspamd to classify content as spam.
• External Authentication - Validates SMTP AUTH credentials against files, LDAP, IMAP, Dovecot, or remote MTAs.
• IP Reputation Scoring - Adjusts a reputation score for each connecting IP based on behavior and known sender history.
• STARTTLS Negotiators - Negotiates STARTTLS to encrypt SMTP sessions between servers or clients.
• SMTP Hook Extenders - Modifies SMTP server logic by attaching custom JavaScript functions to message processing hooks.
• Message Routing Engines - Delivers messages to SMTP, LMTP, webhooks, or message brokers based on recipient rules.
• Hook-Based Plugin Systems - Extends SMTP processing by attaching JavaScript functions to transaction lifecycle hooks for custom message handling.
• Email Filter Pipelines - Routes incoming mail through a sequential chain of plugin hooks for filtering, scoring, and transformation.
• JavaScript Plugin Gateways - Routes messages through custom JavaScript plugins for filtering and processing.
• DNSBL Sender Reputation Checks - Checks connecting IPs and message URIs against DNS blacklists and distributed checksum databases.
• Recipient-Based Routers - Routes incoming messages to different destinations based on recipient address or domain rules.
• SMTP Tarpits - Slows down or defers suspicious connections to mitigate abuse and brute-force attempts.
• Attachment Type Blockers - Blocks or allows email attachments based on file type to enforce content policies.
• SMTP Session Enrichers - Enriches incoming SMTP connections with geographic, ASN, and reputation data from external sources.
• Real-time Traffic Monitoring - Streams live SMTP session data to a web interface for debugging and operational visibility.
• Directory-Backed Recipient Validators - Checks recipient addresses against LDAP, PostgreSQL, Dovecot, or Wild Duck before acceptance.
• Sender Domain MX Validations - Verifies HELO string format and checks that the MAIL FROM domain resolves to an MX record.
• Webhook Forwarders - Ships a plugin that forwards incoming email content to webhook URLs for automated processing.
• SMTP Connection Enrichments - Attaches geographic, ASN, TCP fingerprint, and reverse DNS data to incoming SMTP connections.
• Envelope Sender Rewritings - Applies Sender Rewriting Scheme to preserve SPF alignment during email forwarding.
• Malware Scanning - Inspects message bodies and attachments with ClamAV, AVG, ESET, or other antivirus engines.
• Greylisting Implementations - Defers delivery from unknown senders temporarily to discourage spam and verify sender persistence.
• Behavioral Reputation Adjusters - Dynamically adjusts per-IP reputation scores based on behavioral patterns and sender history.
• Credential Leak Prevention - Scans outgoing messages for passwords or secrets and blocks delivery to prevent data leaks.
• External Service Integrations - Integrates with external services like SpamAssassin, ClamAV, and LDAP for spam, malware, and authentication checks.
• SMTP Transaction Loggers - Sends SMTP transaction metadata to Elasticsearch, syslog, or JSON log files for analysis.
• Email Infrastructure - Listed in the “Email Infrastructure” section of the Awesome Selfhosted awesome list.
• Email Servers - High-performance, plugin-based SMTP server.

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