High performance email marketing engine

An ESP style email client & server built in C for sending large amounts of unique email quickly and efficiently.

Skills & Technologies

POSIX Threads
mbed TLS


The client was the main part of the project.

With a plethora of settings to change every facet of the way the delivery of the email took place over the SMTP connection. Things such as number of connections made at a time, timeouts, SSL connections, SMTP Auth etc.

The client is multithreaded using the POSIX threads library, and event loops (libevent) to achieve the best possible performance. There is a TCP server interface into the client as it runs in realtime to give direct feedback.


A server was built in order to process return mail via SMTP for bounces etc. Again it was build using C, libevent & POSIX Threads.