Try to use TLServer version 3.15 to test the email server setup. You can perform an email test after you have entered the SMTP server ip address and port no. 25. If it works without authentication using port 25 then you can use the same IP address and define it for XServer which will then allow XServer to send email directly.
But if you must use authentication or only support SMTP ports other than 25, then XServer would not be able to use that SMTP server. An alternative is to let XServer connect to TLServer using the <RemoteFS> tag and let TLServer use its more complex SMTP server with authentication etc to help send out the email.