Logging Outgoing Mail from Postfix with Node.js and TeqFW DI

While developing NutriLog, I needed to track all outgoing emails sent through Postfix. This led to the creation of a small tool — smtp-logger.

This is a simple Node.js utility that connects to Postfix as a pipe handler. It receives the complete email via stdin, extracts the sender, recipient, and subject, and saves the entire "raw" MIME structure to a SQL database (PostgreSQL, SQLite, MySQL, etc. via knex).

What makes this project interesting?

It's a working example of using ES6 modules and late dependency binding in JS architecture. The entire structure is built using @teqfw/di — a lightweight DI container compatible with native JavaScript (no TypeScript or bundlers required).

Features

• Integration with Postfix via pipe (e.g., through always_bcc)

• Extraction of from, to, and subject + saving the entire email

• Works with any database supported by knex

• CLI interface: init-db and log commands

• SQLite support for local logging

Important: the database schema is not created automatically. Before use, you must manually run the init-db command.

If you use Postfix only for outgoing mail — this is an excellent solution for auditing, debugging, and logging messages in production or staging environments.