sendmail relay host issue

[sparky_2]

Hello,
In order to send mails externally from a server using sendmail, I have changed the relay host in sendmail.cf as follows:
DS..com
1) the server can successfully resolve the relay host
2) I am able to successfully telnet to port 25 on the relay host.
However, when I try to send mail, the mail.log reports "stat: Service unavailable"

This is the result of a sendmail test:
> sendmail -v @hotmail.com
hello
.
@hotmail.com... Connecting to .com. via relay...
220 .com Microsoft ESMTP MAIL Service, Version: 6.0.3790.1830 ready at Fri, 25 Nov 2005 15:28:24 +0000
>>> EHLO hx000021.
501 5.5.4 Invalid Address
>>> HELO hx000021.
501 5.5.4 Invalid Address
>>> QUIT

Does anyone have any idea about what the EHLO and HELO address errors are referring to? Any assistance greatly appreciated.
Thanks.

[Geoff Wild]

You need to have the full domain name set for your Unix server...

Try masquerading - set the DM macro to:

DMyourdomain.com

Rgds...Geoff

[sparky_2]

Hi Geoff. Thanks for your input, but I already tried that, to no avail.
As it happens, however, I am now able to send mails externally since changing back to the original relay host! I imagine that the next hop is possibly configured to send out via the main SMTP relay already. So once the relevant ports were opened / firewall relaxed, I needn't have changed anything in the sendmail configuration at all!