Spey

Spey is an efficient, easy-to-use SMTP proxy that provides a simple solution for reducing spam in your mail setup. It effectively implements greylisting, which is an ideal way of dealing with spam. By using Spey, you can dramatically reduce the amount of spam you receive, and preserve your bandwidth too.

What's great about Spey is how easy it is to set up. Unlike other options, Spey doesn't require any knowledge of your mail server's usually obtuse configuration system. It's small, fast, and just works, making it a practical option for any user.

Why use greylisting? It's fast, extremely effective, and practically self-maintaining. Greylisting requires the sender to verify that it's a real mail server in a way that is RFC-compliant and invisible to normal users, while at the same time punishing abusers of the email system. It even works on email viruses too.

Spey has helped many users reduce their spam intake from 100 messages a day to just three. It's a simple daemon that listens on the SMTP port. When a remote server connects to it, Spey connects to your real mail server and relays the SMTP transaction. While doing this, it monitors the SMTP conversation to decide whether to greylist the message or allow it to proceed.

Spey is written in Posix-standard C++, using the Sqlite embedded SQL library to store its address database. It runs on most systems, although it has been developed on Linux, and uses very few system resources. With its simple interface and effective greylisting capabilities, Spey is an excellent choice for anyone looking to reduce spam on their email server.