Injecting Using SMTP

KumoMTA will listen for message injection in any listener defined in configuration. You have complete control over the IPs and Ports available for message injection.

The ESMTP Listener will accept any properly formatted SMTP connection request allowed by its configuration. For instance, based on this:

kumo.start_esmtp_listener {
  listen = '0.0.0.0:25',
  hostname = 'mail.example.com',
  relay_hosts = { '127.0.0.1', '10.5.1.0/24' },
}

KumoMTA will accept any SMTP injection from the local host as well as any hosts in the 10.5.1.0/24 CIDR block on port 25. The most basic form of "injection" is to test from localhost using nc or telnet.

ehlo moto
mail from:youremail@address.com
rcpt to:youremail@address.com
DATA
from:youremail@address.com
to:youremail@address.com
subject: My First Email

Hey, this is my first email!
.

If that returns a 250 OK, then any more complex injection should work as well.

Most campaign systems that connect to a third-party MTA have a settings section named something like "SMTP" or "Outbound Email". Enter the SMTP port and the hostname or IP address there, along with your injection username and password if you have configured SMTP_Auth.

Below is a configuration screen for Ongage

And this is a sample of the configuration page for Mautic marketing automation.