Problem with the MAIL command

Hi I have a simple mail command which I can see my SMTP (IIS5) server is picking up but its not sending the email out anywhere - So thought my server was configured wrong - I spent several hours playing with it and got nowhere so I installed a different SMTP server (mercury) onto the same machine - Again I can see the server software is seeing the email come in but again it does nothing with it. On inspection of both SMTP logs I can see PHP issues a HELO and RECPT and then a QUIT command is being issued to the servers ... I think its this SMTP QUIT thats causing the problem but I dont know where to start. Any PHP/SMTP gurus out there ? -- Regards Michael