There are a few possible reasons why mails are not being send out:

• there is an error in the SMTP communication (e.g. the remote server rejects the delivery)
• the SMTP communication is being blocked (e.g. PORT 25 is not opened)
• LUCY is configured to use a mail relay which either is not allowed to relay mails or LUCY is not provided with the correct credentials.
• there is a domain configuration issue. Example: If you configure a scenario, which has specified as a sender email like "user@mydomain.com" configured and also at the same time email forwarding enabled for the domain, Lucy will add the sender email account (and its domain; in this case "mydomain.com") to the internal mail server and waits for incoming email for that user. So if Lucy added mydomain.com to the list of mail domains for incoming mail and you try at the same time to send email using the internal mail server, LUCY will actually not try to send mails anywhere, instead it will try to send mails to itself, assuming mydomain.com mail server is configured on Lucy itself.