Qmail smtproutes

A classic!

smtproutes is a file used by qmail to specify the routing of outgoing mail. It's a simple text file that contains a list of rules to determine where to send outgoing mail.

Here's a breakdown of the format:

• Each line represents a single routing rule.
• The format is: domain host:port
• domain is the domain name for which the rule applies.
• host:port is the hostname and port number of the mail server to use for sending mail to that domain.

For example:

example.com  mx.example.com:25
example.net  mx.example.net:25

In this example, when qmail receives an outgoing email destined for example.com, it will send it to mx.example.com on port 25. Similarly, when it receives an email destined for example.net, it will send it to mx.example.net on port 25.

You can also use wildcards and regular expressions to make the routing rules more flexible. For example:

*.example.*  mx.example.com:25

This rule would match any domain that ends with .example. and send it to mx.example.com on port 25.

The smtproutes file is usually located in the /var/qmail/smtproutes directory, but the exact location may vary depending on your qmail configuration.

When you update the smtproutes file, you'll need to restart the qmail service or run the qmail-smtpd command with the -R option to reload the routing table.

That's it!