Piler

Piler is an email archiving tool designed to handle the long term storage and retrieval of email for organizations that need to meet compliance or legal discovery requirements. It connects to existing mail servers using IMAP or sits directly behind your MTA to capture every message as it flows through. The system stores emails in a compressed, deduplicated format, which cuts storage costs significantly compared to keeping everything in the live mail store.

The software includes a full text search engine built on Sphinx, so you can search across millions of messages by sender, recipient, date range, body content, and attachments. It supports standard email protocols and can be deployed on Linux systems using MySQL or MariaDB as the backend database. There is also a web interface for end users to perform their own searches and export results, reducing the burden on IT staff for simple retrieval requests.

Piler is released under the GPLv3 open source license, making it a budget friendly option for smaller teams and enterprises alike. It was originally created by Janusz Sutkowski and has an active community around it. The project is suitable for anyone who needs a self hosted email archive without the high licensing costs of proprietary appliances.