Rspamd is an advanced spam filtering system and email processing framework designed to evaluate messages through multiple analysis methods. The system employs various rule-based approaches including regular expressions, statistical analysis, and integration with custom services such as URL blacklists. Each processed message receives a verdict that can be utilized by Mail Transfer Agents (MTAs) for subsequent processing decisions, such as message rejection or header modification to indicate spam status. The framework provides additional email processing capabilities including DKIM signature handling and message modification suggestions. Rspamd operates as a Milter, enabling direct integration with popular MTA systems including Postfix and Sendmail. The system is architected to handle high-volume email processing, capable of analyzing hundreds of messages per second simultaneously. It includes a comprehensive Lua API that provides access to various aspects of message processing, along with an asynchronous network API for accessing external resources such as DNS, HTTP, and generic TCP/UDP services.