This software improves the capabilities of corporate mail servers by intercepting SMTP messages, allowing for dynamic modifications, rejection, or retransmission to the server. The software offers extensive customizability and logging, including support for Greylisting and Tarpitting.

One of the major benefits of SMTP Preprocessor is its wide range of settings, which allow you to improve security and add new features to your corporate SMTP server. For example, you can use it to reject connections based on remote host IP address or DNS name (Black List), the presence of a reverse DNS PTR record, the validity of the HELO or EHLO command, and the connections limit.
The program also has the ability to reject the MAIL command based on the sender address (Black List), transactions limit, and message size. Similarly, you can reject the RCPT command based on recipient address (Private Recipients List), recipient domain name (Anti-Relaying), sender address (Restricted Senders List), recipients limit, or based on the Greylisting technology. In addition, you can reject out-of-order SMTP commands, delay the response using Tarpitting technology, and flexibly replace corporate SMTP server response or any SMTP Preprocessor generated response.
SMTP Preprocessor also offers the ability to replace the sender in the SMTP envelope (MAIL command) and recipient in the SMTP envelope (RCPT command). The program keeps an adjustable detailed log of all SMTP events, giving you the insight you need to troubleshoot any issues that may arise.
Overall, SMTP Preprocessor is a must-have software for any mail administrator looking to streamline and secure their corporate mail server. Its range of features and customizable settings make it a powerful tool for enhancing the overall functionality of your email system.
Version 1.11: Fixed some bugs, added new feature