exim

Start mail queue processing

$ exim -q

$ echo "Test" | exim [user@example.com]

$ exim -bp

$ exim -bpc

$ exim -M [message_id]

$ exim -Mrm [message_id]

$ exim -bt [user@example.com]

$ exim -bV

exim [options] [addresses...]

exim is a Mail Transfer Agent (MTA) that handles sending, receiving, and routing email on Unix systems. It's known for flexibility in configuration and filtering capabilities.
The tool supports ACLs, content scanning, TLS encryption, and various authentication mechanisms. It can function as both an incoming and outgoing mail server.

-q [time]

Run queue, optionally repeatedly.

List messages in queue.

Count messages in queue.

Test address routing.

Display version and config.

Force delivery of message.

Remove message from queue.

View message headers.

View message body.

Enable debug mode.

Use alternate configuration.

Complex configuration syntax. Requires careful security setup. Port 25 often blocked by ISPs. Log monitoring essential for production.

Exim was originally written by Philip Hazel at the University of Cambridge starting in 1995. The name stands for "EXperimental Internet Mailer." It became the default MTA for Debian and is widely used on Unix servers.

sendmail(1), postfix(1), mailq(1), mutt(1)