RELAY_DENIED_DYNIP?

Possible reasons:
- You run XMail from an dynamic IP address range or
- there is no domain name assigned to your IP address.

If this error is caused by your dynamic IP address:
Forward mails to that domain to your ISP's SMTP with following entry in smtpfwd.tab:

"target_domain.com"[TAB]"your_isp_smtp.com"[ENTER]

If your ISP's SMTP needs authentication, you need to create a file in /MailRoot/userauth/smtp.
See the Xmail Manual for details (chapter "SMTP CLIENT AUTHENTICATION")