SMTP Auth is acting weird

[mani_jeee]

Hi.

I am on Zimbra 6.0 box and facing issue in SMTP authentication but situation is quite weird. Here it goes. (S=server response, C=client command i.e. me)

On telnet from an XP machine i get the following response

c:\> Telnet myzmserver.mydomain.com smtp

S: 220 myzmserver.mydomain.com ESMTP Postfix
C: ehlo myzmserver.mydomain.com
S: 250-myzmserver.mydomain.com
S: 250-PIPELINING
S: 250-SIZE 10240000
S: 250-VRFY
S: 250-ETRN
S: 250-AUTH PLAIN LOGIN
S: 250-AUTH=PLAIN LOGIN
S: 250-ENHANCEDSTATUSCODES
S: 250-8BITMIME
S: 250-DSN
S: 250 STARTTLS

It shows that auth option is available.
Now when i telnet from a Windows 2008 server the response goes like:

c:\> Telnet myzmserver.mydomain.com smtp

S: 220 myzmserver.mydomain.com ESMTP Postfix
C: ehlo myzmserver.mydomain.com
S: 250-myzmserver.mydomain.com
S: 250-PIPELINING
S: 250-SIZE 10240000
S: 250-VRFY
S: 250-ETRN
S: 250-STARTTLS
S: 250-ENHANCEDSTATUSCODES
S: 250-8BITMIME
S: 250 DSN

As you can see, its the same server but giving out different responses for different clients. I actually need to work it for windows 2008 server.
On Global and server document all seems normal. Infact i am able to relay mails from xp machine but mail from windows 2008 server are rejected for relay denied reason.
What could be the possibility? Any one can shed some light?
I would appreciate your kind reply.


Regards,
Mani