SMTP badmail with PHP

Hi,

I am using Windows server 2003(IIS 6.0).

All the settings are Default. My SMTP server is running.

I can send mails using all my ASP scripts.

But now that I have installed PHP and MySql on my Server, I am trying for 7 continuous days to mail something using my PHP scripts.

The problem is all my mails are going to the BADMAIL folder.

(C:\Inetpub\mailroot\Badmail)

And thats it, I've been trying and trying couldnt find a solution yet.

The following is the error report that gets saved in the BADMAIL folder along with the actual message each time:

----------------------------------------------------------
Unable to deliver this message because the follow error was encountered: "This message is a delivery status notification that cannot be delivered.".

The specific error code was 0xC00402C7.


The message sender was <>.


The message was intended for the following recipients.
URL
--------------------------------------------------------------------

Please anyone, help would be very very much appreciated.

Thanx...

Probably the message sender being blank causes the message to reject.

Just guessing