By default smtp4dev listens on the loopback interface (127.0.0.1) on the standard SMTP port 25 and does not have SSL turned on.

To configure your software to send email to smtp4dev, set the smtp server to "localhost", the port number to 25 and ensure that SSL is turned off. To determine how to do this you should consult the documentation for the SMTP client software/library that you are using.

Connecting from another computer

As of release 2.0.9, smtp4dev only listens on the loopback interface (127.0.0.1) by default. This means that only programs on the same computer will be able to connect. To allow access from another computer on the network, change the listen interface in the options dialog to "any".