...
Solution- Use forwarding SMTP Server.
When NLINK Email Connector is used without a forwarding SMTP server, then NLINK Email acts as SMTP Server. Although not required by SMTP Standard (RFC 2821), as per best practices NLINK will send fully qualified domain name (FQDN) as part of the HELO (or EHLO) command. FQDN is derived based on "Full computer name", and cannot be overwritten. The "Full computer name" can be seen using "Control Panel\System and Security\System".
In case the NLINK host is not part of domain, then sending domail domain will be blank and emails cannot be sent. Only solution is to use a forwarding SMTP Server.
...