Exim/exim
FreeExim Mail Transport Agent - source, testsuite and documentation
FreeFree tier
About Exim/exim
Exim is a highly configurable open-source Mail Transport Agent (MTA) used for routing and delivering email. Originally developed at the University of Cambridge, it is known for its flexibility and extensive configuration options. This repository contains the source code, test suite, and documentation for Exim. As of late 2025, the project has migrated its development off GitHub to its own infrastructure (code.exim.org) but the repository remains as an archived snapshot.
Key Features
Source code for the Exim MTA
Comprehensive test suite
Official documentation
Flexible email routing and delivery
SMTP server implementation
GPL-licensed open source
Pros & Cons
Pros
- Highly configurable and flexible
- Widely used and well-documented
- Open source (GPL) with active community
- Supports extensive mail processing rules
- Long history of stability in production
Cons
- Configuration can be complex for beginners
- Development repository is now archived on GitHub (project moved elsewhere)
- Requires understanding of email infrastructure
Best For
Running a mail server for a domain or organizationEmail routing and relayingSMTP server in enterprise environmentsLearning MTA internals and mail protocols
FAQ
What is Exim?
Exim is a Mail Transport Agent (MTA) used for routing and delivering email on Unix-like systems.
Is Exim still maintained?
Yes, but development has moved off GitHub to the official project site at https://www.exim.org/ and repository at https://code.exim.org/exim/. The GitHub repository was archived as of 2025-12-26.
What license does Exim use?
Exim is licensed under the GNU General Public License (GPL).
Where can I find the official documentation?
Official documentation is available at https://www.exim.org/docs.html.