Why is my Zimbra mail going into the spam folder of yahoo, hotmail etc.?

All mail from my new Zimbra mail server is going into spam and junk folder of Yahoo or Hotmail. Any suggestion to deliver them direct into inbox?

Below is the header part of my mail from yahoo...

X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.963
X-Spam-Level: X-Spam-Status: No, score=-1.963 tagged_above=-10 required=6.6 tests=[AWL=-0.083, BAYES_00=-2.599, RCVD_IN_SORBS_WEB=0.619, RDNS_NONE=0.1] autolearn=no
Received: from mail.sara.co.in ([127.0.0.1]) by localhost (mail.sara.co.in [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id QLBlyaY6ENGi; Fri, 19 Mar 2010 16:52:09 +0530 (IST)
Received:from mail.sara.co.in (mail.sara.co.in [192.168.1.1]) by mail.sara.co.in (Postfix) with ESMTP id 0FC6C3538001; Fri, 19 Mar 2010 16:52:08 +0530 (IST)
Date:   Fri, 19 Mar 2010 16:52:08 +0530 (IST)

I don't see any public IP addresses in your header... Did you send one to yourself? If so, that won't work. We need to see the headers after it arrives at Yahoo or Hotmail.
One thing I do see is that your mail server thinks you are on a SORBS Blacklist. If you are, then Yahoo and Hotmail will most certainly tag your emails as spam...

Update: You are on 5 blacklists according to: MXTOOLBOX. This is for sure the reason you are getting put in the junk folder at Yahoo and Hotmail.