Mail Sent ERROR, Help (Mail not getting sent)

i have configured the SMTP service in nopCommerce admin section with all the credentials required for SMTP service, i am sure about the credentials as all these are working in my another asp.net website.
So, this is my configuration : http://img707.imageshack.us/img707/9531/smtp.jpg

i added products in the card and ordered few products and after completion of this order i was supposed to get a notification e-mail that my order have been placed, but i did'nt get any e-mail
so i check the Message Quote and i saw this: http://img15.imageshack.us/img15/3807/sents.jpg

and in the Log section i saw this ERROR: http://img59.imageshack.us/img59/4670/msgerror.jpg

its not that i should wait for the e-mail, first thing i try this everyday to test the project and even next day or after 2 days too i don't get any e-mail. Secondly, i am getting a message relay error in the log as you can see i guess it proved that message is not being sent.

Please HELP ME OUT WITH THIS PROBLEM

hi abcd - i looked at your screenshots - the problem looks like a your server does not recognise the email address so i tried sending an email to you at

[email protected]

and it was returned with the message:

This is an automatically generated Delivery Status Notification.

Delivery to the following recipients failed.

[email protected]

the problem is not with nopcommerce, you will need to create the email address ...

Hi haydie,
            Could you please tell me what are the permissions i have to give to that e-mail address which i will be using in the SMTP service mailbox configuration ?
I am trying to create a new e-mail address on the exchange server, so please provide me the list of all the permission that needs to be active/allowed in order to work with SMTP mailbox ?

the domain name i registered for my site has been given the nameservers of my hosting company - once that was done, my hosting company associated mailboxes to my domain name ( mail.mydomain.com ) - i set up e-mail addresses and smtp etc with this information