Send mail task

Hello!

I'm trying to set up a send mail task, but even after setting the taks properties or/and the server settings (SMTP server, e-mail address), I still get the following error message:

Failed to connect to email server: null. Reason: Could not connect to SMTP host: localhost, port: 25: com.adobe.idp.dsc.email.ConnectionFailedException: Failed to connect to email server: null. Reason: Could not connect to SMTP host: localhost, port: 25

Does anyone have any idea?

Thanks!